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Frage 1 Bericht
An object is placed 25cm in front of a convex mirror has its image formed 5cm behind the mirror. what is the focal length of the convex mirror
Antwortdetails
Object distance (u) = -25 cm (negative because the object is in front of the mirror)
Image distance (v) = +5 cm (positive because the image is behind the convex mirror)
Using 1f = 1u + 1v
1f = 1−25 + 15
f = 254 = 6.250cm.
Frage 2 Bericht
Electrolysis can be investigated using
Antwortdetails
When investigating electrolysis, the most relevant instrument from the list provided is the Voltameter. This is because the voltameter is specifically designed to measure the amount of substance that is deposited or consumed at electrodes during the electrolysis of an electrolyte. It functions based on the chemical change associated with the electric current passing through the electrolyte.
Here is a simple explanation of how electrolysis works and why a voltameter is useful:
Electrolysis is the process of using electricity to cause a chemical reaction, which is usually a decomposition reaction. This involves passing an electric current through an electrolyte (a substance containing free ions). These ions migrate towards electrodes, resulting in chemical changes. The key aspect to measure during electrolysis is the amount of material (e.g., metal or gas) that is deposited at the electrodes.
The Voltameter helps in understanding electrolysis because:
Voltmeter, Ammeter, and Galvanometer are not used primarily for investigating electrolysis:
Frage 3 Bericht
The energy in a moving car is an example of
Antwortdetails
The energy in a moving car is an example of kinetic energy.
To explain simply, **energy** is the ability to do **work** or cause **change**. There are different forms of energy, and **kinetic energy** is one of them. It is defined as the energy possessed by an object due to its motion.
When a car is moving, it possesses **kinetic energy** because its components are in **motion**. This motion energy allows the car to do tasks, such as transporting people or goods from one place to another. The faster the car moves, the greater its **kinetic energy**, and thus it can make a larger impact or do more work.
In contrast, energy forms like **mechanical energy** is a combination of both kinetic and potential energy; **electrical energy** is associated with electrical charge movement, while **potential energy** is related to the position or condition of an object (like a car parked on a hill). Therefore, the specific type of energy from a moving car is **kinetic energy**.
Frage 4 Bericht
The efficiency of a cell with internal resistance of 2Ω supply current to a 6Ω resistor is
Antwortdetails
To determine the efficiency of a cell with an internal resistance of 2 Ω while supplying current to a 6 Ω resistor, we can use the concept of power dissipation. Efficiency in this context is the ratio of the power delivered to the external resistor to the total power supplied by the cell. It can be calculated using the formula:
Efficiency (%) = (Power across load resistor / Total power output by cell) × 100
Let's break it down step by step:
The efficiency of the cell when supplying current to a 6 Ω resistor with an internal resistance of 2 Ω is 75%.
Frage 5 Bericht
Infra-red thermometers work by detecting the
Antwortdetails
Infra-red thermometers work by detecting the radiation from the body and converting it to temperature. These thermometers are designed to measure the infrared radiation, also known as heat radiation, emitted by objects. All objects with a temperature above absolute zero emit infrared radiation. The thermometer's sensor captures this radiation and converts it into an electrical signal that can be read as a temperature measurement. This method allows for quick, non-contact temperature readings, which is why infrared thermometers are often used in medical settings, industrial applications, and more.
Frage 6 Bericht
Use the diagram above to answer the question that follows
The zone labelled II is called
Antwortdetails
The zone labelled II is called the littoral zone.
To explain: The littoral zone is a part of a body of water that is close to the shore. It is typically characterized by abundant sunlight and nutrient availability, making it a highly productive area for aquatic plants and animals. This zone supports various forms of life such as algae, small fish, and invertebrates. The key feature of the littoral zone is its proximity to the shoreline, where sunlight can penetrate to the bottom, allowing for photosynthesis to occur.
Frage 7 Bericht
A blacksmith heated a metal whose cubic expansivity is 3.9 x 10−6 K−1 . Calculate the area expansivity.
Antwortdetails
To find the area expansivity of a metal when given its cubic expansivity, you should understand the relationship between linear, area, and cubic expansivity.
Cubic expansivity (\( \beta \)) is defined as the fractional change in volume per change in temperature, and is given by the formula:
\[ \Delta V = \beta V \Delta T \]
Area expansivity (\( \alpha_{A} \)) corresponds to the fractional change in area per change in temperature and can be derived from the linear expansivity (\( \alpha \)). The relationship between these expansivities is as follows:
\[ \text{Area Expansivity (\( \alpha_{A} \))} = 2 \times \text{Linear Expansivity (\( \alpha \))} \]
The cubic expansivity (\( \beta \)) is related to the linear expansivity by:
\[ \text{Cubic Expansivity (\( \beta \))} = 3 \times \text{Linear Expansivity (\( \alpha \))} \]
Thus, based on these relationships, we can express the area expansivity in terms of the cubic expansivity:
\(\text{Area Expansivity (\( \alpha_{A} \))} = \frac{2}{3} \times \text{Cubic Expansivity (\( \beta \))}
Given that the cubic expansivity \( \beta \) is \( 3.9 \times 10^{-6} \, \text{K}^{-1} \):
The area expansivity can be calculated as follows:
\[ \text{Area Expansivity (\( \alpha_{A} \))} = \frac{2}{3} \times 3.9 \times 10^{-6} \, \text{K}^{-1} = 2.6 \times 10^{-6} \, \text{K}^{-1} \]
Therefore, the **correct answer** is **2.6 x 10^{-6} K^{-1}**.
Frage 8 Bericht
A mass of gas at 40mmHg is heated from 298k to 348k at constant volume. Cal the pressure exerted by the gas.
Antwortdetails
To determine the new pressure exerted by the gas when it is heated, we'll apply **Gay-Lussac's Law**. This law states that at constant volume, the pressure of a given amount of gas is directly proportional to its absolute temperature. Mathematically, it can be expressed as:
P1/T1 = P2/T2
Where:
By rearranging the formula to solve for the final pressure (P2), we get:
P2 = P1 * (T2/T1)
Now, insert the given values into the equation:
P2 = 40 mmHg * (348 K / 298 K)
Perform the calculations:
P2 = 40 mmHg * (348 / 298)
P2 = 40 mmHg * 1.1678
P2 = 46.71 mmHg
So, the new pressure exerted by the gas when it is heated from 298 K to 348 K at constant volume is 46.71 mmHg.
Frage 9 Bericht
Two points on a velocity-time graph have coordinates (2s, 5m/s) and (4s, 15m/s). Calculate the mean acceleration
Antwortdetails
The mean acceleration of an object is determined by the change in velocity over the change in time. This is given by the formula:
Mean Acceleration (a) = (Final Velocity - Initial Velocity) / (Final Time - Initial Time)
From the velocity-time graph, we have the following points:
Initial Point: (2s, 5m/s)
Final Point: (4s, 15m/s)
Here, the Initial Velocity is 5m/s, the Final Velocity is 15m/s, the Initial Time is 2s, and the Final Time is 4s.
Plug these values into the formula:
Mean Acceleration (a) = (15m/s - 5m/s) / (4s - 2s)
Simplifying this, we get:
Mean Acceleration (a) = 10m/s / 2s = 5m/s²
The mean acceleration is therefore 5.0 m/s².
Frage 10 Bericht
A boy standing 408m from a wall blew a trumpet and heard the echo 2.4s later. Calculate the speed of the sound
Antwortdetails
To calculate the speed of sound, we need to understand that an echo involves a sound wave traveling to a surface and back. In this case, the sound travels from the boy to the wall and then returns.
The total distance that the sound wave travels is twice the distance from the boy to the wall because it goes to the wall and back. Therefore, the total distance is:
Total Distance = 2 x 408m = 816m
The echo was heard 2.4 seconds after the sound was made. The speed of sound can be calculated using the formula:
Speed of Sound = Total Distance / Time
Plugging in the values, we have:
Speed of Sound = 816m / 2.4s
When you perform the division, you find:
Speed of Sound = 340 m/s
Thus, the speed of the sound is 340 m/s, which is the correct answer.
Frage 11 Bericht
The stress experienced by a wire of diameter
Antwortdetails
Stress is defined as the force applied per unit area. In the context of a wire being loaded by a weight, the weight acts as the force exerted, and the cross-sectional area of the wire is the area over which this force is distributed.
Force (F): This is given by the weight, which is y2 N.
Cross-sectional Area (A): For a wire with a diameter, the area can be calculated using the formula for the area of a circle: A = πr2, where r is the radius of the wire.
Given the diameter of the wire as yπ meters, the radius (r) is half of the diameter:
r = (yπ)/2
So, the area (A) is:
A = π[(yπ)/2]2
Simplifying the area:
A = π(y2π2/4)
A = y2π3/4
Stress (σ) is given by the formula:
σ = F/A
Substituting the given weight (force) and the calculated area:
σ = (y2) / (y2π3/4)
By simplifying the expression:
σ = (4y2) / (y2π3)
Cancel out y2 from numerator and denominator:
σ = 4/π2 Nm−2
Thus, the correct stress experienced by the wire is 4π Nm−2, as provided in one of the options. The explanation shows clearly how the force and area are used to derive the stress experienced by the wire.
Frage 12 Bericht
Calculate the magnetic force on an electron in a magnetic field of flux density 10T, with a velocity of 3 x 107 m/s at 60º to the magnetic field (e = 1.6 x 10−19 C)
Antwortdetails
The magnetic force on an electron in a magnetic field (F) = q v Bsinθ
B = 10T, q = 3 x 107 m/, θ = 60º and q = 1.6 x 10−19 C
F = 1.6 x 10−19 x 3 x 107 x 10 x sin 60º ≊ 4.162 × 10−11 N
Frage 13 Bericht
Which of the following structures enables the exchange of gases in insects?
Antwortdetails
In insects, the structure responsible for the exchange of gases is the tracheae. Insects have a unique respiratory system where air is taken in through tiny openings called spiracles located on the surface of their body.
The air then travels directly into a network of tubes known as the tracheae. The tracheae branch out extensively throughout the insect's body, allowing oxygen to diffuse directly to the insect's tissues and cells. The carbon dioxide produced in the cells travels back through the tracheae and exits the body through the spiracles.
Other structures like the skin, Malpighian tubules, and flame cells have different functions:
Thus, the correct answer is the tracheae as they specifically enable the exchange of gases in insects.
Frage 14 Bericht
The major building block of an organism is...
Antwortdetails
The major building block of an organism is Carbon. Let me explain why in a simple yet comprehensive manner:
Carbon is a unique element found in all living organisms. Its importance comes from its ability to form stable bonds with many other elements, including hydrogen, oxygen, nitrogen, phosphorus, and sulfur. This versatility allows carbon to act as a backbone for the building of complex organic molecules, including proteins, nucleic acids (such as DNA and RNA), carbohydrates, and lipids. These molecules are essential for the structure, function, and regulation of the body's tissues and organs.
Here's why Carbon is indispensable:
In summary, Carbon is the primary building block of life due to its unique chemical properties that allow the formation of complex molecules necessary for life's structure and processes.
Frage 15 Bericht
The bursting of water pipes during very cold weather, when the water in the pipes form ice could be attributed to
Antwortdetails
The bursting of water pipes during very cold weather is primarily attributed to the expansion of water on freezing.
Here's why this happens:
1. **Normal water behavior below freezing:** Typically, when most substances freeze, they contract because the molecules get closer together. However, water behaves differently due to its unique molecular structure. As water freezes, it forms a crystalline structure that makes ice less dense than liquid water, causing it to expand.
2. **Effect of expansion:** When water inside a pipe freezes, it expands. This expansion puts tremendous pressure on the pipe walls because the solid ice takes up more space than the liquid water. Most pipes are rigid and do not have enough room to accommodate the expanded volume of ice.
3. **Resulting pressure:** The increased pressure caused by the expanding ice can cause the pipe to crack or burst, especially if there is no other outlet for the water or ice to expand into.
In summary, pipes burst during cold weather primarily due to the expansion of water as it freezes, which creates pressure that the pipe cannot withstand. This phenomenon is due to the unique property of water where it expands upon freezing, unlike most other substances which contract in their solid form.
Frage 16 Bericht
5 X 10−3 kg of liquid at its boiling point is evaporated in 20s by the heat generated by a resistor of 2Ω when a current of 10A is used. The specific latent heat of vaporization of the liquid is
Antwortdetails
To solve this problem, we need to calculate the specific latent heat of vaporization of the liquid. The specific latent heat of vaporization, denoted as \(L\), is defined as the amount of heat required to convert 1 kilogram of a liquid into a gas at constant temperature and pressure. The formula for specific latent heat of vaporization is given by:
L = \(\frac{Q}{m}\)
Where:
First, we need to calculate the total heat energy \(Q\) generated by the resistor. The heat produced by an electrical resistor can be calculated using the formula:
Q = I^2Rt
Where:
Given:
Substituting these values into the formula for Q:
Q = (10^2) * 2 * 20 = 100 * 2 * 20 = 4000 J
Now that we have the total heat energy supplied, let's calculate the specific latent heat of vaporization:
Given that the mass \(m\) of the liquid evaporated is \(5 \times 10^{-3}\) kg, we can substitute the values into the formula for \(L\):
L = \(\frac{4000}{5 \times 10^{-3}} = \frac{4000}{0.005} = 800,000 J/kg\)
Therefore, the specific latent heat of vaporization of the liquid is 8.0 x 105 J/kg.
Frage 17 Bericht
The quantity of heat required to melt ice of 0.2 kg whose specific latent heat is 3.4 x 105 J/Kg is
Antwortdetails
To determine the quantity of heat required to melt ice, we use the formula for latent heat:
Q = m × L,
where:
For this problem, we have:
Now, substitute these values into the formula:
Q = 0.2 kg × 3.4 × 105 J/kg
Calculate the product:
Q = 0.68 × 105 J
To express this in standard scientific notation, it can be rewritten as:
Q = 6.8 × 104 J
Thus, the quantity of heat required to melt 0.2 kg of ice is 6.8 × 104 J.
Frage 18 Bericht
The fourth overtone of a closed pipes is 900Hz, its fundamental frequency is
Antwortdetails
To solve this problem, let's first understand how sound works in a closed pipe. A closed pipe has one end closed and another end open. Sound waves inside such a pipe create standing waves, where nodes (points of no movement) and antinodes (points of maximum movement) are formed.
For a closed pipe, the fundamental frequency (also called the first harmonic) has one node at the closed end and one antinode at the open end. The wavelength is four times the length of the pipe.
The overtone sequence for a closed pipe includes only odd harmonics: 1st (fundamental), 3rd, 5th, 7th, etc. The nth overtone is the 2nth + 1 harmonic. The equation for the frequency of a harmonic in a closed pipe is:
f_n = n * f_1, where f_n is the frequency of the nth harmonic and f_1 is the fundamental frequency
In this case, the fourth overtone corresponds to the 9th harmonic because 2 * 4 + 1 = 9. Therefore, we have:
900 Hz = 9 * f_1
To find the fundamental frequency (f_1), we solve for f_1:
f_1 = 900 Hz / 9
f_1 = 100 Hz
Therefore, the fundamental frequency is 100 Hz.
Frage 19 Bericht
A load of 300N is to be lifted by a machine with a velocity ratio of 2 and an efficiency of 60%. What effort will be applied to lift the load?
Antwortdetails
To determine the effort needed to lift a load using a machine, we first need to understand some key concepts: **Load**, **Effort**, **Velocity Ratio** (VR), and **Efficiency**.
1. **Load** is the force or weight that needs to be lifted by the machine. In this case, the load is 300N.
2. **Velocity Ratio (VR)** is the ratio of the distance moved by the effort to the distance moved by the load. Given here as 2.
3. **Efficiency** of a machine is expressed as a percentage and is the ratio of the useful work output to the input work done by the effort. Here, the efficiency is 60% or 0.60 as a decimal.
The formula to calculate the **Effort** is derived from the relationship between these factors:
\[ \text{Efficiency} = \frac{\text{Mechanical Advantage (MA)}}{\text{Velocity Ratio (VR)}} \]
Where:
\[ \text{Mechanical Advantage (MA)} = \frac{\text{Load}}{\text{Effort}} \]
From the above, we have:
\[ \text{MA} = \text{VR} \times \text{Efficiency} \]
Replacing with the given values:
\[ MA = 2 \times 0.60 = 1.2 \]
Now, calculate the **Effort** using the relation:
\[ \text{Effort} = \frac{\text{Load}}{\text{MA}} \]
\[ \text{Effort} = \frac{300N}{1.2} = 250N \]
Therefore, the **Effort** needed to lift the load is 250N.
Frage 20 Bericht
Calculate the value of electric field intensity due to a charge of 4μC if the force due to the charge is 8N
Antwortdetails
To calculate the electric field intensity due to a charge, we need to use the formula:
Electric Field Intensity (E) = Force (F) / Charge (q)
In this problem, we are given that the force (F) is 8 Newtons (N) and the charge (q) is 4 microcoulombs (μC). First, we need to convert the charge from microcoulombs to coulombs:
1 microcoulomb (μC) = 1 x 10-6 coulombs (C)
Therefore, 4 μC = 4 x 10-6 C.
Now we can use the formula to find the electric field intensity:
E = F / q
E = 8 N / (4 x 10-6 C)
E = 8 / 4 x 106
E = 2 x 106
Thus, the value of the electric field intensity is 2 x 106 N/C.
Frage 21 Bericht
A solid cube of aluminum is 1.5cm on each edge. The density of aluminum is 2700kgm−1 . Find the mass of the cube.
Antwortdetails
The mass of an object can be calculated using the formula:
Mass = Density × Volume
In this case, we need to find the mass of a solid cube of aluminum. Given:
First, we need to calculate the volume of the cube. The volume V of a cube with edge length a is given by:
V = a3
Substitute the edge length:
V = (1.5 cm)3 = 1.5 × 1.5 × 1.5 cm3 = 3.375 cm3
Since the density is given in kg/m3, we should convert the volume from cm3 to m3. There are 1,000,000 cm3 in 1 m3, so:
Volume in m3 = 3.375 cm3 × (1 m3/1,000,000 cm3) = 3.375 × 10-6 m3
Now, use the mass formula:
Mass = Density × Volume
Mass = 2700 kg/m3 × 3.375 × 10-6 m3
This equals:
Mass = 9.1125 × 10-3 kg
Convert kg to grams (since 1 kg = 1000 g):
Mass = 9.1125 grams
So, the mass of the cube is approximately 9.1 g. Thus, the correct answer is 9.1 g.
Frage 22 Bericht
Which of the following materials has a very large energy gap band?
Antwortdetails
An insulator is a material that has a very large energy gap between its valence band and conduction band. To understand this, let's first consider the concept of energy bands: In materials, electrons exist in different energy levels. These levels form bands called the valence band and the conduction band. A material is classified based on the size of the energy gap between these bands.
Thus, insulators have a very large energy gap band, making them poor conductors of electricity.
Frage 23 Bericht
The degree of precision of a vernier caliper is
Antwortdetails
The degree of precision of a vernier caliper is actually the **smallest value** that the vernier scale can measure, which can be considered as the resolution or least count of the instrument. The degree of precision for most standard vernier calipers is 0.01 cm (or 0.1 mm). This means that the caliper can measure dimensions down to a hundredth of a centimeter.
To understand why this is the case, consider the construction of a vernier caliper:
This alignment allows more precise measurements than the main scale alone. If the vernier scale has 10 divisions which coincide over a length equal to 9 divisions on the main scale, then each division of the vernier scale represents an extra 0.01 cm. Therefore, it allows measuring smaller intervals between the main scale markings very precisely.
Thus, you won't find vernier calipers with a degree of precision of 0.005 cm, 0.1 cm, or 1.0 cm as options in standard practice for precise measurement tools.
Frage 24 Bericht
Use the diagram above to answer the question that follows
The organism belongs to kingdom
Antwortdetails
The diagram is that of the virus. Viruses are obligate parasites, meaning they can't produce their own energy or proteins. They enter the host cell and use the cell's machinery to make their own nucleic acids and proteins. Viruses also use the host cell's lipids and sugar chains to create their membranes and glycoproteins. This parasitic replication can severely damage the host cell, which can lead to disease or cell death. They usually enter your body through your mucous membranes. These include your eyes, nose, mouth, penis, vagina and anus.
Viruses are a unique type of organism that are not plants, animals, or bacteria. They are often classified in their own kingdom. However, for the sake of the question, since most of their attributes and metabolic activities are more of the bacteria, we'll go with option A - Monera
Frage 25 Bericht
Inbreeding is highly discouraged in humans because it may
Antwortdetails
Inbreeding is the process where closely related individuals, like cousins or siblings, mate and produce offspring. **This practice is highly discouraged in humans for several reasons, but a significant concern is the potential for an outbreak of hereditary diseases.**
Here’s why inbreeding is problematic:
Therefore, **to promote genetic diversity and reduce the risk of hereditary diseases in offspring, inbreeding is discouraged in human populations**. This way, offspring are less likely to inherit harmful genetic combinations that can lead to health problems.
Frage 26 Bericht
In the diagram above, the galvanometer is converted to
Antwortdetails
To determine what the galvanometer is converted to in the described scenario, let’s first understand how a galvanometer can be transformed into different measuring devices:
1. Galvanometer to Voltmeter: To convert a galvanometer into a voltmeter, a high resistance (known as a multiplier) is connected in series with the galvanometer. This high resistance ensures that the voltmeter can measure a wide range of voltages without drawing significant current from the circuit.
2. Galvanometer to Ammeter: To convert a galvanometer into an ammeter, a low resistance (called a shunt) is connected in parallel with the galvanometer. This allows the majority of the current to pass through the shunt, enabling the ammeter to measure high currents without damaging the galvanometer.
Since the problem statement does not specify any additional details, a general observation is that a galvanometer is commonly converted into an ammeter using a shunt, especially in basic electrical circuits where current measurement is necessary. Therefore, from the options provided, **the galvanometer is most likely converted to an ammeter**.
**In summary**, if a low resistance is added in parallel with the galvanometer, it becomes an ammeter, while adding a high resistance in series would convert it into a voltmeter. Since the context commonly involves conversion for current measurement, the provided diagram likely represents a galvanometer converted into an ammeter.
Frage 27 Bericht
The average translational kinetic energy of gas molecules depends on
Antwortdetails
The average translational kinetic energy of gas molecules is directly related to the temperature of the gas. This relationship is based on the principles of kinetic molecular theory, which explains the behavior of gas molecules in terms of their motion.
Let's break this down simply:
1. Temperature and Kinetic Energy:
The average translational kinetic energy of gas molecules is given by the equation:
\( KE_{avg} = \frac{3}{2} k_B T \)
where \( KE_{avg} \) is the average translational kinetic energy, \( k_B \) is the Boltzmann constant, and \( T \) is the absolute temperature in Kelvin. This formula shows that the kinetic energy is directly proportional to the temperature.
2. What This Means:
As the temperature of a gas increases, the molecules move faster, which increases their translational kinetic energy. Conversely, as the temperature decreases, the molecules slow down, resulting in lower kinetic energy.
It is important to note that this relation is independent of the pressure and the number of moles of the gas. While pressure and the number of moles do affect the overall behavior of a gas, they do not directly influence the average translational kinetic energy of individual molecules.
Therefore, the correct explanation is that the average translational kinetic energy of gas molecules depends on temperature only.
Frage 28 Bericht
The unit of impedance is
Antwortdetails
The unit of impedance is Ohm, which is symbolized by the Greek letter Ω (Omega). In electrical circuits, impedance (Z) is a measure of opposition that a circuit offers to the passage of electric current when a voltage is applied. It is similar to resistance but extends to alternating currents (AC) and contains the effects of resistance as well as reactance (which accounts for capacitors and inductors).
Just like resistance, the unit of impedance is the ohm because they measure similar concepts; however, impedance also accounts for phase shifts between voltage and current, which are not considered in simple resistance. Ohm's Law is used in AC circuits as Z = V/I, where Z is impedance, V is voltage, and I is current. This relationship shows why the unit of impedance is the same as that of resistance.
Frage 29 Bericht
Using the circuit above, at resonance
Antwortdetails
To understand the concept of resonance in an electrical circuit, it is crucial to know that resonance occurs when the inductive reactance and capacitive reactance are equal in magnitude. This typically happens in a series RLC (Resistor, Inductor, Capacitor) circuit. At resonance, the impedance of the circuit is purely resistive, meaning the circuit behaves as if it only contains a resistor. As a result, the voltages across the inductor and capacitor can be compared at resonance.
In this particular situation, the voltage across the inductor (VL) and the voltage across the capacitor (VC) are of interest due to their roles in resonance:
Thus, the correct expression of interest in relation to resonance is VL = VC, which indicates that the voltage across the inductor is equal in magnitude but opposite in phase to the voltage across the capacitor.
Frage 30 Bericht
The moon's acceleration due to gravity is 16 of the earth's value. The weight of a bowling ball on the moon would be
Antwortdetails
To determine the weight of a bowling ball on the moon, we need to understand the relationship between weight, gravity, and mass.
Weight is the force exerted by gravity on an object. On Earth, this force depends on the object's mass and the acceleration due to gravity, which is approximately 9.8 m/s². Weight can be calculated using the formula:
Weight = Mass x Gravity
On the moon, the acceleration due to gravity is only 1/6 of Earth’s gravity. This means the gravitational pull on the moon is much weaker compared to the Earth. If we take the Earth's gravity to be 9.8 m/s², the moon's gravity would be:
Moon's Gravity = (9.8 m/s²) x (1/6) ≈ 1.63 m/s²
Given that the weight of an object is directly proportional to the gravitational force, the weight of an object on the moon would be substantially less than its weight on Earth. Thus, the weight of the bowling ball on the moon would be:
Weight on Moon = (Mass) x (1.63 m/s²) = 1/6 of its weight on Earth
Therefore, the weight of a bowling ball on the moon is 1/6 of its weight on Earth.
Frage 31 Bericht
The gravitational force between two objects masses 1024 kg and 1027 kg is 6.67N. Calculate the distance between them [ G = 6.6 x 10−11 Nm2 kg−2 ]
Antwortdetails
To calculate the distance between two objects based on the gravitational force acting between them, we need to use the formula for gravitational force:
F = (G * m1 * m2) / r²
Where:
We need to compute r by rearranging the formula:
r² = (G * m1 * m2) / F
Therefore, the distance r is:
r = √((G * m1 * m2) / F)
Substitute the given values into the equation:
r = √((6.6 x 10-11 Nm²/kg² * 1024 kg * 1027 kg) / 6.67 N)
Calculating inside the square root:
G * m1 * m2 = 6.6 x 10-11 * 1024 * 1027 = 6.6 x 1040 Nm²
Then divide by the force:
6.6 x 1040 Nm² / 6.67 N = 0.99 x 1040 m²
Finally, calculate the square root:
r = √(0.99 x 1040)
r ≈ 1.0 x 1020 m
Therefore, the distance between the two objects is approximately 1.0 x 1020 m.
Frage 32 Bericht
The diaphragm in the camera is similar to what part of the eyes?
Antwortdetails
The diaphragm in a camera is similar to the iris in the human eye.
Here's a simple explanation:
In summary, the iris acts like a natural diaphragm, regulating the light that passes through the eye, much like the diaphragm does in a camera.
Frage 33 Bericht
Which of the following is the best as shaving mirror?
Antwortdetails
When selecting the best type of mirror for shaving, the key consideration is how the mirror reflects light and creates an image. For the purpose of shaving, it is important to have a mirror that magnifies the face and provides a clear view.
The best option for a shaving mirror is a concave mirror. Here is why:
Other types of mirrors, like convex and plane mirrors, and parabolic mirrors, do not provide the same level of magnification or focused reflecting properties, making them less suitable for shaving purposes.
Frage 34 Bericht
Which of the following operates based on magnetic effect of electric current?
Antwortdetails
The device that operates based on the magnetic effect of electric current is the Dynamo.
To explain further, let's look at the concept of the magnetic effect of electric current:
A Dynamo is a device that converts mechanical energy into electrical energy. It operates based on the phenomenon called electromagnetic induction, which occurs due to the magnetic effect of electric current. When a coil of wire within the dynamo rotates in the presence of a magnetic field, it induces an electric current in the coil. Thus, the operation of a dynamo relies on the interaction between electric current and magnetic fields.
To contrast with other options:
Frage 35 Bericht
If a charge ion goes through a combined electric field E and magnetic field B, the resultant emergent velocity of the ion is
Antwortdetails
The resultant emergent velocity of a charged ion moving through combined electric and magnetic fields can be derived from the condition where the electric force equals the magnetic force. This gives us the formula for the velocity v:
q E = qvB
v = EB (q will cancel out)
NOTE: When both fields are present, for the ion to move without deflection, the electric force must equal the magnetic force.
Frage 36 Bericht
Find the value of a capacitor with voltage 5V and 30C.
Antwortdetails
To find the value of the capacitance, we need to use the formula for capacitance:
Capacitance (C) = Charge (Q) / Voltage (V)
In this problem, the charge (Q) is given as 30 Coulombs (C) and the voltage (V) is 5 Volts (V). We can plug these values into the formula:
C = 30 C / 5 V
Calculating the above expression gives:
C = 6 Farads (F)
Therefore, the value of the capacitor is 6 Farads.
Frage 37 Bericht
When a cell of e.m.f 3.06V is connected, the balance of a potentiometer is 75cm, Calculate the new balance of a cell of e.m.f 2.295V
Antwortdetails
To solve this problem, we first need to understand the principle behind a potentiometer. A potentiometer is a device used to measure the electromotive force (e.m.f) of a cell by comparing it with a known voltage. The balance length on a potentiometer corresponds to a proportional measurement of the e.m.f.
Let's denote:
- \( V_1 \): the e.m.f of the first cell = 3.06V
- \( l_1 \): the balance length for the first cell = 75 cm
- \( V_2 \): the e.m.f of the second cell = 2.295V
- \( l_2 \): the balance length for the second cell (which we need to find)
The basic relationship for a potentiometer is given by:
\( V_1 / V_2 = l_1 / l_2 \)
Substituting the given values:
\( 3.06 / 2.295 = 75 / l_2 \)
We need to solve for \( l_2 \):
\( l_2 = (2.295 \times 75) / 3.06 \)
Now, calculating the above expression:
\( l_2 = 171.975 / 3.06 \approx 56.26 \) cm
Therefore, the new balance length for the cell with an e.m.f of 2.295V is approximately 56.26 cm.
Frage 38 Bericht
The force of attraction between molecules of the same substance is
Antwortdetails
The force of attraction between molecules of the same substance is called cohesion.
To understand this simply:
Cohesion refers to the attractive forces acting between similar molecules. For example, water molecules attract each other due to hydrogen bonding, which is a strong intermolecular force.
Let's break down some important concepts:
In summary, **cohesion** is the force that keeps the molecules of the same substance, like water, attracting each other.
Frage 39 Bericht
As per Faraday's laws of electromagnetic induction, an e.m.f is induced in a conductor whenever
Antwortdetails
According to Faraday's laws of electromagnetic induction, an electromotive force (e.m.f) is induced in a conductor whenever it **cuts magnetic flux**. This means that for an e.m.f to be induced, the conductor must move in such a way that it intersects the magnetic lines of force. It is the relative motion between the conductor and the magnetic field that leads to the change in magnetic flux, resulting in the induction of e.m.f.
Let's explore why this is the correct answer using reasoning:
Therefore, the phenomenon where a conductor cuts magnetic flux is essential for electromagnetic induction as per Faraday's laws.
Frage 40 Bericht
The land and sea breeze is attributed to
Antwortdetails
The phenomenon of land and sea breeze is primarily attributed to convection.
To understand this, let's first look at what land and sea breezes are:
Land Breeze: At night, the land cools down faster than the sea. The cooler, denser air from the land moves towards the sea, and this is known as a land breeze.
Sea Breeze: During the day, the land heats up more quickly than the sea. The warmer, lighter air over the land rises, and the cooler air from the sea moves in to take its place. This movement of air from the sea to the land is known as a sea breeze.
Both of these processes involve the movement of air due to differences in temperature and density, which is essentially the process of convection.
Convection is the transfer of heat through a fluid (like air or water) and is responsible for moving air masses and creating these breezes. The warm air, being less dense, rises, and the cooler, denser air moves in to replace it.
In contrast, conduction is the transfer of heat through a solid material, and radiation is the transfer of heat in the form of electromagnetic waves, neither of which primarily drive the processes of these breezes, making convection the key player.
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