Physics (9-1) 0972 | Paper 1 Mock 01 | Multiple Choice (Core)

The correct answer is vacuum flask. The best insulator is the container that loses the least heat, and the vacuum flask drops only 3 °C in 20 minutes compared to 19 °C for the plastic cup, 28 °C for the glass beaker and 41 °C for the metal can. The vacuum between its double walls prevents heat loss by conduction and convection, and the silvered surfaces reduce radiation.

The correct answer is a micrometer screw gauge. A micrometer measures to 0.01 mm, making it the most suitable for the small diameter of a thin wire. A metre rule (1 mm divisions) is far too imprecise, a stopwatch measures time not length, and a measuring cylinder measures volume.

The correct answer is m/s². Acceleration is change of velocity (m/s) divided by time (s), giving \(\frac{\text{m/s}}{\text{s}}=\text{m/s}^2\). m/s is the unit of speed, m is distance and s is time.

The correct answer is gamma rays. Photon energy rises with frequency, so gamma rays at the top of the spectrum carry the most energy and are the most strongly ionising. Radio waves and infra-red are low-frequency, low-energy regions, and visible light sits in the middle, all far less ionising.

The correct answer is They are isotopes of the same element. Both atoms have the same proton number (8), so they are the same element (oxygen). They have different nucleon numbers (16 and 18), meaning they contain different numbers of neutrons (8 and 10 respectively). Atoms of the same element with different neutron counts are called isotopes. They are not different elements, not ions, and they do not have the same number of neutrons.

The acceleration of free fall (often written as \( g \)) is a well-known constant near the Earth's surface. Its value is approximately 9.8 m/s² (often rounded to 10 m/s² in calculations).

This means that every second an object is in free fall, its downward speed increases by about 9.8 m/s (ignoring air resistance).

The value 100 m/s² and 20 m/s² are far too large, and 0.98 m/s² is ten times too small. Knowing that \( g \approx 9.8 \text{ m/s}^2 \) (or \( \approx 10 \text{ m/s}^2 \)) is a fundamental fact required throughout the IGCSE Physics course.

After warming, the arrows on the particles are longer, indicating the particles are moving faster. Faster particles have greater kinetic energy, since \( E_k = \frac{1}{2}mv^2 \). Therefore the average kinetic energy of the particles has increased.

Temperature is directly related to the average kinetic energy of the particles. When a gas is heated, energy is transferred to the particles, increasing their speed and thus their kinetic energy. The kinetic energy cannot fall to zero (the particles are still moving), stay the same (the arrows are clearly longer), or decrease (the gas was warmed, not cooled).

The acceleration is 2.5 m/s\(^2\). From \( F = ma \), \( a = \dfrac{F}{m} = \dfrac{5000}{2000} = 2.5\ \text{m/s}^2 \). The value 0.4 m/s\(^2\) inverts the fraction \( \left( \tfrac{2000}{5000} \right) \), 2500 m/s\(^2\) and 400 m/s\(^2\) come from misplacing the decimal or multiplying, so only \( \tfrac{5000}{2000} \) gives the correct 2.5 m/s\(^2\).

The correct answer is Wednesday. Reading the table, Wednesday produced 240 kWh, which is greater than Thursday (210 kWh), Monday (180 kWh), and Tuesday (150 kWh).

Counting the black dots (electrons) in the diagram: the inner shell (smaller circle around the nucleus) holds 2 electrons, and the outer shell (larger circle) holds 4 electrons. The total is 2 + 4 = 6 electrons, consistent with carbon having proton number 6. The other options do not match the number of dots shown.

Convection requires the bulk movement of fluid (liquid or gas) particles. In a solid, the particles are locked in fixed positions within a regular lattice and cannot flow from one region to another. Therefore, even though the heated end has more energetic particles, they cannot physically move through the solid to carry the energy - they can only vibrate and pass energy to neighbours by conduction. The claim that solids have too many free electrons, are always colder than liquids, or contain no thermal energy are all false.

The correct answer is that short-wave radiation enters, but the warmed inside re-emits longer-wave radiation that is trapped. Short-wave radiation from the Sun passes through the glass and is absorbed by the plants and soil, which warm up and re-radiate at longer infrared wavelengths that the glass does not transmit, so the energy stays inside. Convection of cold air inward would cool it, not warm it; the glass does not reflect all radiation away, and it is a poor conductor, so heating by conduction is not the cause.

The rising air over the sea is replaced by Cooler air flowing out from the land. At night the land cools faster than the sea, so the air over the warmer sea rises; cooler, denser air over the land then flows out to the sea at ground level to replace it, giving a land breeze. No replacement being needed, or warm air flowing from the land, would break the circulation, since air must move in to fill the gap left by the rising air.

Temperature is the measure of the average kinetic energy of the particles in a substance. When a metal block is heated without changing state, the particles vibrate faster, meaning their average kinetic energy increases. This increase in kinetic energy is detected and measured as a rise in temperature.

Heating a metal block does not change its mass (mass is conserved and does not depend on temperature) or its weight (which depends on mass and gravitational field strength, neither of which changes with heating). A solid metal block does not produce gas when heated below its boiling point, so "volume of gas produced" is not relevant here.

The correct answer is that a shiny, polished surface is a poor absorber and a good reflector of radiation. The arrows show most of the incoming radiation bouncing off rather than being absorbed, which is exactly how a polished silver surface behaves. Radiation is not conducted, and a shiny surface is also a poor emitter, not a good one, so it neither absorbs strongly nor radiates strongly.

The correct answer is that particles at the hot end vibrate more strongly and pass energy to neighbouring particles. In a non-metal solid the particles are fixed in place by bonds, so heating makes them vibrate harder and they hand kinetic energy on to their neighbours down the rod. Convection cannot happen because the particles cannot flow, they do not leave their fixed positions, and a non-metal has no free electrons to carry the energy.

The correct answer is removes energy from the skin as the fastest particles escape. As water evaporates from the damp cloth, the most energetic particles escape from the surface, taking thermal energy away from the cloth and the skin beneath it. This lowers the average kinetic energy of the remaining water and cools the skin. Evaporation does not seal warm air against the skin, does not add heat energy, and its cooling effect is well established - not "no effect."

The correct answer is that its particles move about and spread to fill the container. A gas has no shape of its own because its particles move freely and spread out to occupy whatever space is available, taking the shape of the container. The particles are not joined in a rigid frame, not frozen in place, and not too heavy to move, all of which would prevent the free movement that a gas actually has.

Radiation (infra-red) transfers the energy from the bonfire to your face. Thermal radiation is an electromagnetic wave that travels through the air (and even through a vacuum) at the speed of light. You feel the warmth on your face because infra-red radiation emitted by the fire is absorbed by your skin.

Conduction requires direct contact between materials. Evaporation is a cooling process. Convection carries warm air upward from the fire, not sideways to your face (the air between you and the fire is cool, confirming convection is not the mechanism here).

As the diagram shows, gas particles are in continuous random motion, moving in all directions and repeatedly striking the container walls. Each collision between a particle and a wall exerts a tiny force on the wall. When this bombardment is averaged over the entire wall surface and over time, the cumulative effect of all these collisions produces a steady force per unit area.

Force per unit area is the definition of pressure. The gas pressure is therefore the macroscopic result of the microscopic collisions of vast numbers of particles with the container walls.

Weight and mass are properties of the gas as a whole, not the result of wall bombardment. Volume describes the space the gas occupies, not the effect of collisions. Pressure is the only quantity that directly corresponds to the average force exerted per unit area by the particle bombardment.

The correct answer is 40°. The law of reflection states that the angle of incidence equals the angle of reflection. Every other row in the table confirms this (10 = 10, 25 = 25, 60 = 60), so the missing value for a 40° angle of incidence must also be 40°.

The best change is to use a spanner with a longer handle. The moment is force times distance from the pivot, so a longer handle increases the distance and produces the same turning effect with a smaller force. A shorter handle or holding nearer the nut both reduce the distance and so need a larger force, and pushing in line with the handle gives no perpendicular distance and therefore no turning moment at all.

The rate at which an object emits thermal radiation increases with its temperature. The hotter an object is, the more infrared radiation it emits per second. Since the bar at 600 °C is at a much higher temperature than the bar at 300 °C, it radiates energy at a significantly greater rate.

In fact, the rate of radiation is proportional to the fourth power of the absolute temperature (the Stefan-Boltzmann law), so even a moderate increase in temperature produces a dramatic increase in radiation output. Both bars have identical surfaces and dimensions, so the only variable is temperature. The diagram illustrates this by showing more radiation waves leaving the hotter bar. Neither bar stops emitting radiation at any temperature above absolute zero.

Power is defined as the rate of energy transfer: \( P = \frac{E}{t} \), where \( E \) is energy in joules and \( t \) is time in seconds. The SI unit of power is the watt (W), where 1 W = 1 J/s.

The newton is the SI unit of force, the pascal is the SI unit of pressure, and the joule is the SI unit of energy. Since power is energy per unit time, not energy itself, the joule alone is not sufficient. Dividing joules by seconds gives watts.

The correct answer is that it reduces energy loss by convection, by stopping warm air escaping and cold air entering. The gap under a door lets warm room air leave and cold outside air flow in, a convection exchange, and the brush seals that gap. Cooling the door would be conduction, reflecting radiation describes a shiny foil, and evaporation from the walls is not involved.

With the heater near the top, Only the upper water gets hot; the lower water stays cold. Warm water is less dense and stays where it is made, so no convection current forms to carry energy downward; the cold water below cannot rise. Because water is a poor conductor, very little energy reaches the bottom, so the tank does not heat evenly.

A liquid that is less dense than another does not sink into it, because a given volume of the less dense liquid weighs less than the same volume of the denser liquid, so it experiences a net upward force and rises above it. Since oil (0.9 g/cm³) is less dense than water (1.0 g/cm³), the oil rises to the top and forms a separate layer floating on the water rather than mixing with it or sinking.

The oil cannot mix evenly with the water (oil and water are immiscible) or sink or collect at the sides; the density difference alone determines that it settles as a layer on top.

The amplitude of a wave is the maximum displacement from the equilibrium (rest) position. On a transverse wave diagram, this is the vertical distance from the central horizontal line to either the crest or the trough.

Looking at the labelled distances in the diagram:

• P is the horizontal distance from one crest to the next crest, which measures the wavelength.
• Q is a horizontal distance covering half a wavelength.
• S is the total vertical distance from the crest to the trough, which equals twice the amplitude.
• R is the vertical distance from the rest position (the horizontal line) to the crest. This matches the definition of amplitude exactly.

A common mistake is to confuse R with S. The full crest-to-trough height (S) is double the amplitude. Amplitude is always measured from the rest position to one extreme, giving R as the correct answer.

Using \(c = f\lambda\), rearrange for wavelength:

\[\lambda = \frac{c}{f} = \frac{3.0 \times 10^8}{6.0 \times 10^{14}} = 5.0 \times 10^{-7} \text{ m}\]

This is 500 nm, which lies in the visible light range and matches green light. The option \(1.8 \times 10^{23}\) m comes from multiplying \(c \times f\). The option \(5.0 \times 10^{-6}\) m has the wrong power of ten. The option \(2.0 \times 10^{6}\) m uses \(f/c\) instead of \(c/f\).

The correct answer is the ball on the steel rod. Steel is the poorest conductor of the four metals, so energy travels along it most slowly and its wax takes longest to soften, making its ball the last to drop. Copper is the best conductor and its ball falls first, with brass and iron falling before steel.

The correct answer is that they are unlike poles and attract. Field lines running straight and unbroken from one magnet across the gap into the other show a N pole facing a S pole, and unlike poles attract. Like poles would repel, and their lines would bend apart rather than cross the gap.

The correct answer is 20 cm. The wavelength is the distance for one complete cycle of the wave, and the graph completes one full wave between 0 cm and 20 cm before repeating. Reading 40 cm counts two whole waves, and 10 cm is only half a wave, so both are wrong.

The correct answer is a balance. A balance compares or measures mass directly in grams or kilograms. A forcemeter measures force (weight) in newtons, a stopwatch measures time, and a thermometer measures temperature.

The correct answer is 3 cm. The amplitude is the maximum displacement from the rest position (the dashed line). From the grid, the wave peaks 3 squares above the equilibrium line, and each square represents 1 cm, so the amplitude is 3 cm. Choosing 6 cm confuses amplitude with the full crest-to-trough distance (which is twice the amplitude). Choosing 1 cm or 2 cm under-counts the number of squares from equilibrium to peak.

The pressure at a point in a liquid due to the liquid above it is given by:

\[ p = \rho g h \]

where \(\rho\) is the density of the liquid, \(g\) is the gravitational field strength, and \(h\) is the depth below the surface.

Substituting the given values:

\[ p = 800 \times 10 \times 0.5 = 4000 \text{ Pa} \]

A common error is to confuse which quantities to multiply. All three must be multiplied together. If you only multiply two of the three values, you get 400, 4000, or 1600 depending on which pair you choose. With all three, the answer is 4000 Pa.

The right-hand end of the left magnet is a N pole, and the left-hand end of the right magnet is a S pole. A N pole and a S pole are unlike poles, so they attract each other. The curved field lines linking the two ends in the diagram show the field running from the N pole to the S pole across the gap, which is the characteristic pattern of attraction.

Like poles (N-N or S-S) repel, but unlike poles (N-S) always attract. The field lines between attracting poles curve smoothly from one magnet to the other, whereas between repelling poles the field lines push outward and a neutral point may form between them.

The excess pressure of the gas above atmospheric pressure equals the pressure produced by the extra height of liquid on the open side. Using \( p = \rho g h \) with density = 1000 kg/m³, g = 10 N/kg, and \( h \) = 0.20 m:

\[ p = 1000 \times 10 \times 0.20 = 2000 \text{ Pa} \]

20000 Pa comes from using 2 m instead of 0.20 m. 200 Pa uses 0.02 m, and 20 Pa uses 0.002 m. The key step is converting 20 cm to 0.20 m before substituting.

The correct answer is mass : newton. The newton is the SI unit of force, not mass. The SI unit of mass is the kilogram. All other pairings are correct: current is measured in amperes, length in metres, and time in seconds.

A thermal is a rising column of warm, less dense air (a convection current). Ground warmed by the Sun heats the air above it, which expands, becomes less dense and rises as a column, and a glider circling in it is carried upward. It is not a conduction current or a downward flow of cold air, and it is a movement of air, not a beam of radiation.

The correct answer is A (a beta particle has a much smaller mass than an alpha particle). In a magnetic field a charged particle moves on a circular arc of radius \( r = \frac{mv}{qB} \), so the smaller the mass \( m \), the tighter the curve and the greater the deflection. A beta particle is an electron with roughly \( \frac{1}{7000} \) of the mass of an alpha particle, so for the same field it is bent far more sharply along the strongly curved path.

Gamma radiation is uncharged and is not deflected at all, so it cannot push the beta particles sideways; a beta particle certainly does carry charge (it is negative); and nothing can move faster than light. The mass difference dominates over the fact that the alpha has the larger charge.