Loading....
Press & Hold to Drag Around |
|||
Click Here to Close |
Question 1 Report
A refrigerator uses 150W. If it is kept on for 336 hours non-stop, what is the energy consumed in KWh?
Answer Details
To calculate the energy consumption of an appliance, you can use the formula:
Energy (in KWh) = Power (in kW) × Time (in hours)
First, convert the power rating of the refrigerator from watts (W) to kilowatts (kW). Since 1 kW is equal to 1000 W, you can convert 150W to kilowatts by dividing by 1000:
150 W = 0.150 kW
Next, calculate the energy consumed over the period the refrigerator is kept on, which is 336 hours. Use the formula:
Energy = 0.150 kW × 336 hours
Now, perform the multiplication:
Energy = 50.40 kWh
Therefore, when the refrigerator is kept on for 336 hours non-stop, it consumes 50.40 kWh of energy. This is the correct choice.
Question 2 Report
Which of the following measuring instruments operates based on the heating effect of electric current?
Answer Details
Hot wire ammeters measure current by detecting the heat produced in a wire due to the electric current flowing through it.
Question 3 Report
A mass of gas at 40mmHg is heated from 298k to 348k at constant volume. Cal the pressure exerted by the gas.
Answer Details
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.
Question 4 Report
Electrolysis can be investigated using
Answer Details
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:
Question 5 Report
The stress experienced by a wire of diameter
Answer Details
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.
Question 6 Report
If the displacement of a car is proportional to the square of time, then the car is moving with
Answer Details
When we say that the displacement of a car is proportional to the square of time (d ∝ t²), it indicates a relationship between displacement (d) and time (t). This relationship is characteristic of motion where there is constant acceleration. Essentially, it means that the car is not moving at a constant speed (velocity) but is accelerating at a constant rate.
The mathematical representation of this scenario can be expressed using the formula for displacement under uniform acceleration:
d = ut + (1/2)at².
In this equation:
When the displacement is directly proportional to the square of time (d ∝ t²), it implies that the second term of the equation, which contains the (1/2)at² part, dominates the relationship. Thus, the initial velocity (u) is typically zero or negligible, making the entire displacement dependent on how time squared interacts with acceleration.
Therefore, the car is moving with uniform acceleration.
Question 7 Report
The value of R in the above circuit to make the galvanometer measure 2A is
Answer Details
Given: Ig = 50mA = 0.05A, I to be measured = 2A, r = 2Ω , Is = I - Ig = 2 - 0.05 = 1.95A
Shunt(R) = IgIs x r
R = 0.051.95 x 10 = 0.2564Ω
Question 8 Report
Using the diagram above, the effective force pushing it forward at an angle 60º is
Answer Details
To determine the effective force pushing the object forward at an angle of 60º, we need to resolve the given force into its components. Specifically, we are interested in the horizontal component of the force, as this is the part that effectively pushes the object forward.
The general formula to calculate the horizontal component of a force (Fx) when the force is applied at an angle (θ) is:
Fx = F * cos(θ)
Where:
Assuming the magnitude of the force applied (F) is 50N, then the effective forward force can be calculated as follows:
Fx = 50N * cos(60º)
Using the trigonometric value:
cos(60º) = 0.5
Therefore:
Fx = 50N * 0.5
Fx = 25N
Hence, the effective force pushing it forward at an angle of 60º is 25.00N. Therefore, the correct answer is 25.00N.
Question 9 Report
The energy stored in the above capacitor is
Answer Details
The energy stored in the capacitor = 12 q2C
Where C = 2F, q = 3C
= 12 322 = 94 = 2.25J
Question 10 Report
A solid cube of aluminum is 1.5cm on each edge. The density of aluminum is 2700kgm−1 . Find the mass of the cube.
Answer Details
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.
Question 11 Report
The formation of cilia and flagella in living cells is carried out with the help of
Answer Details
The formation of cilia and flagella in living cells is primarily carried out with the help of **centrioles**.
Here's a simple explanation:
Centrioles are cylindrical structures made up of microtubules. They are found in eukaryotic cells and play a critical role in cell division and the organization of the cell's cytoskeleton. However, their role extends beyond this to the formation of the basal bodies which seed the growth of cilia and flagella.
Cilia and flagella are microscopic, hair-like structures that protrude from the surface of certain eukaryotic cells. They are primarily involved in movement. Cilia often work like tiny oars, moving fluid across the cell's surface or propelling single-celled organisms. Flagella are typically longer and move in a whip-like fashion to propel cells, such as sperm cells.
Here's how centrioles contribute to the formation of these structures:
1. **Basal Body Formation**: Each cilium or flagellum grows out from a structure known as a basal body. The basal body is derived from the centrioles. During this process, a centriole migrates to the cell's surface and acts as a nucleation site for the growth of microtubules, which in turn form the structural core of cilia and flagella.
2. **Microtubule Organization**: The centrioles help organize microtubules in a "9+2" arrangement, which is characteristic of cilia and flagella. This refers to nine pairs of microtubules forming a ring around two central microtubules, giving these structures both stability and flexibility for movement.
Thus, centrioles are crucial as they provide the groundwork for the formation and proper functioning of cilia and flagella. They ensure that these structures are assembled correctly and are able to carry out their roles in cell movement and fluid transport.
Question 12 Report
How much joules of heat are given out when a piece of iron, of mass 60g and specific heat capacity 460JKg−1 K−1 , cools from 75ºC to 35ºC
Answer Details
To find out how much heat is given out when the piece of iron cools down, we can use the formula for heat transfer:
Q = mcΔT
Where:
First, let's list the values given and convert the mass from grams to kilograms:
Now, calculate the change in temperature:
ΔT = final temperature - initial temperature = 35ºC - 75ºC = -40ºC
Note: Since we are calculating the heat given out as the iron cools, the temperature change will be negative, which will make Q positive, indicating heat is released.
Substitute these values into the heat transfer formula:
Q = mcΔT = (0.06 kg) x (460 J/Kg·K) x (-40ºC)
Q = 0.06 x 460 x -40
Q = -1104 Joules
Since the question asks for how much heat is given out, we consider the positive value of Q, which is 1104J. Therefore, 1104J of heat is given out when the piece of iron cools from 75ºC to 35ºC.
Question 13 Report
If a body in linear motion changes from point P to Q, the motion is
Answer Details
When a body moves in a straight line from one point, such as point P, to another point, such as point Q, the motion is called Translational Motion. This kind of motion refers to an object moving along a path in which every part of the object takes the same path as a reference point. This means that if you follow any point on the body, it covers the same amount of distance in the same time frame as any other point.
Let's break down the other options:
In conclusion, since the body is moving from point P to point Q along a straight line, it exhibits Translational Motion.
Question 14 Report
The quantity of heat required to melt ice of 0.2 kg whose specific latent heat is 3.4 x 105 J/Kg is
Answer Details
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.
Question 15 Report
Infra-red thermometers work by detecting the
Answer Details
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.
Question 16 Report
Pilots uses aneroid barometer to know the height above sea level because
Answer Details
Aneroid barometers are compact and lightweight, making them suitable for use in aircraft where space and weight are critical considerations. They provide a reliable measurement of altitude based on changes in atmospheric pressure.
Question 17 Report
Answer Details
To solve this problem, we need to understand the relationship between pressure, volume, and temperature of a gas. The relevant law here is the **Combined Gas Law**, which is expressed as:
(P1 * V1) / T1 = (P2 * V2) / T2
Where:
In the given problem:
Applying the Combined Gas Law:
(P1 * V1) / 300 = (2 * P1 * V2) / 400
Simplifying this equation:
V1/300 = 2V2/400
Multiply both sides by 400 to clear the fraction:
400 * V1 / 300 = 2 * V2
Which further simplifies to:
(4/3) * V1 = 2 * V2
Dividing both sides by 2:
(2/3) * V1 = V2
This shows that the final volume, V2, is **2/3 of the initial volume, V1**. Therefore, the volume of the gas will **decrease by 1/3**.
Question 18 Report
The thermometer whose thermometric property is change in volume with temperature is
Answer Details
A thermometer that relies on the **thermometric property** of **change in volume with temperature** is the **Liquid-in-glass thermometer**.
Here is why:
1. **Construction**: A liquid-in-glass thermometer consists of a **glass tube** that encloses a small reservoir filled with a **thermometric liquid**, typically mercury or colored alcohol.
2. **Principle of Operation**: As the **temperature** changes, the **volume of the liquid** inside the tube changes. When the temperature rises, the liquid **expands** and moves up the tube. Conversely, when the temperature decreases, the liquid **contracts** and moves down the tube.
3. **Scale Calibration**: The thermometer has graduations marked along the tube, allowing the user to read the temperature by observing the level of the liquid against these scale markings.
Therefore, the liquid-in-glass thermometer operates on the principle that the **volume of a liquid changes with temperature**, making it the correct answer.
Question 19 Report
When thermal energy in a solid is increased, the change in state is called
Answer Details
When the thermal energy in a solid is increased, the solid particles gain energy and begin to vibrate more vigorously. As the temperature rises, these particles eventually have enough energy to overcome the forces holding them in their fixed positions. This leads to a change of state from a solid to a liquid. This process is known as melting.
To further understand this, imagine an ice cube. As it absorbs heat, it gains energy, and the ice (which is a solid) starts to turn into water (which is a liquid). This transition is what we refer to as melting.
Thus, the term that describes this change of state, when a solid is heated and turns into a liquid, is melting.
Question 20 Report
At absolute zero temperature, the average velocity of the molecules
Answer Details
At absolute zero temperature, which is defined as 0 Kelvin or -273.15 degrees Celsius, the energy of molecular motion ceases. This means that the molecules theoretically have minimal energy, and hence, their motion stops entirely. Therefore, the average velocity of the molecules is zero. In reality, absolute zero is a theoretical limit, and it is practically unreachable, but it serves as a concept to help in understanding the behavior of molecules at extremely low temperatures. Thus, under this theoretical condition, the average motion of molecules would be nonexistent. In summary, the average velocity of the molecules at absolute zero is zero.
Question 21 Report
Use the diagram above to answer the question that follows
The diagram above is
Answer Details
The diagram in the image represents the urinary system, as indicated by the correct answer. The urinary system includes the kidneys, ureters, bladder, and urethra, which are responsible for filtering blood and excreting waste in the form of urine.
Kidneys – Filter waste and excess fluids from the blood to form urine.
Ureters – Tubes that carry urine from the kidneys to the bladder.
Urinary Bladder – Stores urine before it is expelled from the body.
Urethra – A tube that allows urine to exit the body.
This system plays a crucial role in maintaining the body's fluid balance and removing waste products.
Question 22 Report
The value of R required to make the galvanometer measure voltage up to 40V in the diagram above
Answer Details
In a galvanometer setup intended to measure voltages, you often encounter a configuration known as a voltmeter, where a resistor is added in series with the galvanometer to increase its range of measurement.
The basic principle is that the total resistance of the voltmeter (comprising the galvanometer's resistance and the additional series resistor) allows it to handle a higher voltage by limiting the current that flows through the galvanometer. The maximum voltage (V) that can be measured by the galvanometer is determined by Ohm's Law: V = I * R,
Where:
Assuming the galvanometer has a known internal resistance (G) and a known full-scale current (I_fullscale), the resistance R required in series can be calculated via the formula:
R = (V / I_fullscale) - G
For this solution, you need either the values of G and I_fullscale or their product (G * I_fullscale). Without those exact specifications provided, it would be imprudent to give an exact numeric answer.
However, if this is a typical example and you have a typical galvanometer with a full-scale current of 50 μA and an internal resistance of 500 Ω, you can compute:
R = (40 / 50 x 10^-6) - 500 = 2000 - 500 = 1500 Ω
Therefore, you would need an additional R = 1990 Ω - 1500 Ω = 490 Ω, meaning the closest possible practical value from your choices is 1990 Ω (including the internal resistance).
If the specific parameters of the galvanometer differ, adjust the calculation accordingly, but the general process is as laid out here.
Question 23 Report
At a pressure of 105 Nm−2 , a gas has a volume of 20m3 . Calculate the volume at 4 x 105 Nm−2 at constant temperature.
Answer Details
In order to solve this problem, we can apply **Boyle's Law**, which states that the **pressure** and **volume** of a gas are inversely proportional at a constant temperature. Mathematically, this is expressed as:
P1V1 = P2V2
Where:
Rearranging the formula to solve for V2:
V2 = (P1V1) / P2
Substituting the given values:
V2 = (105 Nm-2 x 20 m3) / (4 x 105 Nm-2)
By calculating:
V2 = (2100 m3) / 4 x 105
V2 = 5 m3
Therefore, at a pressure of 4 x 105 Nm-2, the volume of the gas is 5 m3.
Question 24 Report
Rainbow is formed when sunlight undergoes
Answer Details
A rainbow is formed through a combination of three processes: reflection, refraction, and dispersion. Let's break down each process to understand how a rainbow forms:
1. Refraction: When sunlight enters a raindrop, it bends or changes direction. This bending of light is known as **refraction**. Different colors of sunlight bend by different amounts because they have different wavelengths.
2. Reflection: Once inside the raindrop, the light gets reflected off the inside surface of the drop. This reflection sends the light back out of the raindrop at different angles.
3. Dispersion: As the light exits the raindrop, it bends again (refraction). Because each color bends by a different amount, the sunlight is spread out into its component colors, creating a spectrum. This spreading into a spectrum is called **dispersion**.
All three processes contribute to the formation of a rainbow. The combination of **refraction, reflection, and dispersion** results in the beautiful arc of colors that we see in the sky.
Question 25 Report
The power of a convex lens of focal length 20cm is
Answer Details
The power of a lens is a measure of its ability to converge or diverge light. It is defined as the reciprocal (or inverse) of the focal length of the lens. The formula for calculating the power (P) of a lens in diopters (D) is given by:
P = 1/f
where:
In this case, the focal length given is 20 cm. To apply the formula, we first need to convert this focal length into meters because the diopter is the reciprocal of the focal length in meters:
f = 20 cm = 0.20 m
Now, substitute the focal length in meters into the formula for power:
P = 1 / 0.20
P = 5.00 D
Thus, the power of the convex lens is 5.00 diopters. This indicates that the lens is capable of converging light at a distance of 5.00 meters.
Question 26 Report
Which of the following structures enables the exchange of gases in insects?
Answer Details
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.
Question 27 Report
The tangential force acting on an object that opposes it from sliding freely on the adjacent surface is called
Answer Details
The tangential force acting on an object that opposes it from sliding freely on the adjacent surface is called the friction force.
Let me explain each of the options to clarify why friction force is the correct answer:
In summary, friction force is the force that acts to oppose sliding between surfaces in contact and acts tangentially, making it the correct answer.
Question 28 Report
In electrolysis, when same quantity of electricity is passed through different electrolytes, mass of substances deposited is proportional to
Answer Details
In electrolysis, when the same quantity of electricity is passed through different electrolytes, the mass of substances deposited is proportional to their chemical equivalent. The reason for this lies in Faraday's laws of electrolysis. Faraday's second law states that the amounts of different substances deposited or liberated by the same quantity of electricity are proportional to their chemical equivalents.
Chemical equivalent refers to a measure of a substance's ability to react or be deposited during electrolysis, and it is calculated as the molar mass divided by valency (n). This is why it is sometimes also referred to as equivalent weight.
In essence, for a given charge (equal number of electrons or electricity), a substance with a lower chemical equivalent will deposit more mass because it requires fewer electrons to undergo the chemical change.
Question 29 Report
A blacksmith heated a metal whose cubic expansivity is 3.9 x 10−6 K−1 . Calculate the area expansivity.
Answer Details
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}**.
Question 30 Report
In a cross involving a heterozygous red flower plant (Rr) and a white flowered plant (rr). What is the probability that the offspring will be Rr?
Answer Details
By crossing Rr x rr
We obtain Rr , rr , rr , Rr
⇒ 50% = 12
Question 31 Report
Bilateral symmetry,cylindrical bodies and double openings are characteristic features of
Answer Details
Bilateral symmetry, cylindrical bodies, and double openings are characteristic features of nematodes. Nematodes, also known as roundworms, have a body structure that is symmetric along a single plane, which results in two mirror-image halves, thus exhibiting bilateral symmetry.
Furthermore, they usually have a cylindrical body shape, which means their bodies are long and narrow like a cylinder and taper at both ends. This shape helps them move through their environment easily. Additionally, nematodes have a complete digestive system with two openings: a mouth and an anus. This means that food enters through the mouth, gets digested, and waste exits through the anus.
In contrast, organisms like hydra, protozoa, and protists possess different anatomical features. Hydras, for example, typically show radial symmetry, and protozoa and protists generally do not have a well-defined body shape or bilateral symmetry as seen in nematodes. Therefore, the description fits nematodes best.
Question 32 Report
Two capacitors of 0.0003μF and 0.0006μF are connected in series, find their combined capacitance.
Answer Details
When capacitors are connected in series, the formula to find their combined capacitance \(C_{\text{total}}\) is given by:
\[ \frac{1}{C_{\text{total}}} = \frac{1}{C_1} + \frac{1}{C_2} \]
where \(C_1\) and \(C_2\) are the capacitances of the individual capacitors. In this case, \(C_1 = 0.0003 \, \mu\text{F}\) and \(C_2 = 0.0006 \, \mu\text{F}\).
First, calculate the reciprocal of each capacitance:
\[ \frac{1}{C_1} = \frac{1}{0.0003} \]
\[ \frac{1}{C_2} = \frac{1}{0.0006} \]
Calculating each value:
\[ \frac{1}{0.0003} = \frac{10^6}{3} \] and \[ \frac{1}{0.0006} = \frac{10^6}{6} \]
Now, add these values together:
\[ \frac{1}{C_{\text{total}}} = \frac{10^6}{3} + \frac{10^6}{6} = \frac{10^6 \times 2}{6} + \frac{10^6 \times 1}{6} = \frac{10^6 \times 3}{6} = \frac{10^6}{2} \]
Finally, take the reciprocal of the resulting value to find \(C_{\text{total}}\):
\[ C_{\text{total}} = \frac{2}{10^6} = 0.0002 \, \mu\text{F} \]
So, the combined capacitance of the two capacitors in series is 0.0002 μF.
Question 33 Report
Use the diagram above to answer the question that follows
The zone labelled II is called
Answer Details
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.
Question 34 Report
Calculate the power of an object which moves through a distance of 500cm in 1s on a frictionless surface by a horizontal force of 50N
Answer Details
To calculate the power of an object, we need to use the formula for power in terms of work done over time. The formula is:
Power (P) = Work Done (W) / Time (t)
First, let's find the work done on the object. Work done can be calculated using the formula:
Work Done (W) = Force (F) × Distance (d)
Given:
Substituting the values into the formula for work done, we get:
Work Done (W) = 50 N × 5 m = 250 Joules
Next, we consider the time it took for the object to move this distance:
Now, substituting the work done and time into the power formula:
Power (P) = 250 Joules / 1 s = 250 Watts
Thus, the power of the object is 250 Watts.
Question 35 Report
A sonometer's fundamental note is 50Hz, what is the new frequency when the tension is four times the original?
Answer Details
To solve this problem, we need to understand the relationship between tension and frequency in a sonometer wire. The frequency of a vibrating string, such as one in a sonometer, is directly proportional to the square root of the tension in the string. Mathematically, this relationship is expressed as:
f ∝ √T
Where f is the frequency and T is the tension. In the given problem, the original frequency is 50 Hz, and the tension is increased to four times its original value. Let's analyze how this change in tension affects the frequency:
- Original tension = T
- New tension = 4T
Substitute the new tension into the formula:
f_new = 50 Hz × √(4T/T)
Simplify the equation:
f_new = 50 Hz × √4
f_new = 50 Hz × 2
f_new = 100 Hz
Thus, when the tension is four times the original tension, the new frequency of the sonometer's fundamental note becomes 100 Hz.
Question 36 Report
The average translational kinetic energy of gas molecules depends on
Answer Details
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.
Question 37 Report
In voltage measurement, the potentiometer is preferred to voltmeter because it
Answer Details
In voltage measurement, a **potentiometer is preferred to a voltmeter** primarily because it **consumes negligible current**. Let me explain this in simpler terms:
A **voltmeter** is an instrument used to measure the potential difference (voltage) across two points in an electrical circuit. However, when a voltmeter is connected, it draws a small amount of current from the circuit to make the measurement, which can slightly alter the voltage being measured. This is particularly an issue in high-resistance circuits where even a small current draw can significantly affect the measurement.
On the other hand, a **potentiometer** is a device designed to measure voltage by comparing it with a known reference voltage without drawing current from the circuit under test. It comes into balance at a point where no current flows through it, ensuring that the measurement is not influenced by the potentiometer itself. This makes it a non-invasive method of measuring voltage, which is particularly useful for precise measurements in sensitive circuits.
Here’s a brief explanation about why the other options listed are less relevant:
Therefore, the key advantage of the potentiometer is its **ability to measure voltage without altering the circuit**, which stems from its negligible current consumption. This **ensures more accurate and reliable measurements** in many applications.
Question 38 Report
A practical application of total internal reflection is found in
Answer Details
A practical application of total internal reflection is found in fiber optics.
To understand this, let's break it down:
When light travels from one medium to another (such as from glass to air), it changes direction. This is known as refraction. However, there is a phenomenon called total internal reflection which occurs when light is traveling within a denser medium towards a less dense medium (like from glass to air) and hits the boundary at an angle greater than a certain critical angle. Instead of passing through, the light is completely reflected back into the denser medium.
Fiber optics technology makes use of this principle. In fiber optics, light is transmitted along the core of a thin glass or plastic fiber. The core is surrounded by another layer called the cladding. This cladding has a lower refractive index than the core, which facilitates total internal reflection. As a result, the light continuously reflects internally along the length of the fiber, allowing it to travel long distances with minimal loss.
This property is harnessed in various applications such as in high-speed telecommunication systems, medical equipment like endoscopes, and other technologies that require the transmission of data over long distances with high efficiency.
Question 39 Report
Answer Details
To understand when a vapor is considered saturated, it is crucial to consider the rates of two significant processes: evaporation and condensation. **Evaporation** is the process where liquid molecules escape into the vapor phase, and its rate is denoted as **y**. On the other hand, **condensation** is the process where vapor molecules return to the liquid phase, with its rate denoted as **x**.
A vapor is said to be **saturated** when the rate of evaporation of the liquid is equal to the rate of condensation of the vapor. In simpler terms, the number of molecules leaving the liquid to become vapor is exactly equal to the number of molecules returning from the vapor to the liquid.
In mathematical terms, this condition can be described as **x = y**. Under this condition, the system reaches a dynamic equilibrium, and the vapor pressure of the system is at its maximum for the given temperature. At this point, the vapor cannot accommodate any more molecules, and thus, the vapor is in a saturated state.
Question 40 Report
Which of these gas laws is equivalent to workdone
Answer Details
To understand which of these gas laws is equivalent to work done, we must first understand the basic concept of work in the context of gases. For gases, work is done when there is a change in volume under pressure, typically expressed as W = P ΔV, where W is work, P is pressure, and ΔV is the change in volume.
Let's consider the given gas laws:
Among these, Boyle's law relates directly to work done because it involves a change in volume at constant temperature, implying that work occurs as a gas expands or compresses. The equation P₁V₁ = P₂V₂ is foundational for calculating work done in reversible processes, which aligns with the expression for work done on a gas, W = P ΔV. Thus, **Boyle's law** is most directly connected to the concept of work done on a gas.
Would you like to proceed with this action?