Cambridge IGCSE Physics - 0625 - Supplement Paper 4 2015 Winter Zone 3

A plastic ball is dropped from the balcony of a tall building and falls towards the ground in a straight line.

Fig. 1.1 is the speed-time graph for the falling ball.



(a) State and explain, in terms of forces, what is happening to the speed of the ball between time $t = 2.0\,s$ and $t = 3.0\,s$.
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(b) On Fig. 1.1, mark a point P on the line where the acceleration of the ball is not constant. [1]

(c) Using Fig. 1.1,
(i) calculate the acceleration of the ball between $t = 0\,s$ and $t = 0.25\,s$,

acceleration = ....................................................[2]

(ii) estimate the distance that the ball falls in the first $3.0\,s$.

distance = ....................................................[2]

A student has 500 identical, rectangular sheets of paper. The mass of 1.0 $\text{m}^2$ of the paper is 0.080 kg.
(a) Using a metre rule, she measures the length of one sheet of paper and its width. The length is 0.300 m and the width is 0.210 m.
(i) Calculate the mass of one sheet of paper.

mass = ............................................................[1]

(ii) The student makes a single pile of the 500 sheets of paper.
With a metre rule, she measures the height of the pile. The height of the pile is 0.048 m.
Calculate the density of the paper.

density = ............................................................[3]
(b) A second student has only 5 sheets of the same type of paper.
Suggest how this student determines the density of the paper to a similar accuracy. Additional apparatus may be used.
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Fig. 3.1 shows part of the extension-load graph for a spring.

The spring obeys Hooke’s law between points A and B.
(a) (i) On Fig. 3.1, complete the graph between A and B. [1]
(ii) State the name of point B.
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(b) The average value of the load between A and B is 6.0N.
Calculate the work done in extending the spring from A to B.
work done = ...................................................... [2]
(c) The spring has an unstretched length of 4.0 cm.
An object is hung on the spring and the spring length increases from 4.0 cm to 6.0 cm.
(i) Calculate the mass of the object.
mass = ....................................................... [3]
(ii) The object is immersed in a liquid but remains suspended from the spring.
The liquid exerts an upward force on the object and the length of the spring decreases to 5.0 cm.
Calculate the upward force exerted on the object by the liquid.
upward force = .............................................. [2]

A soft rubber ball of mass 0.15 kg is dropped, in a vacuum, from a height of 2.0 m on to a hard surface. The ball then bounces.
(a) State the main energy changes taking place when
(i) the ball is falling, ........................................................................................................................................................
(ii) the ball hits the surface and is changing shape, ........................................................................................................................................................
(iii) the ball is regaining its shape and is rising from the surface. ........................................................................................................................................................ [3]
(b) Calculate the speed with which the ball hits the surface.

speed = ........................................................ [4]
(c) After rebounding from the surface, the ball rises to a height of 1.9 m. Suggest why the height to which the ball rises is less than the height from which the ball falls. ........................................................................................................................................................ ........................................................................................................................................................ [1]

(a) State two examples of physical properties that vary with temperature and that may be used for the measurement of temperature.
1. ............................................................
2. ............................................................
[2]
(b) When first manufactured, a liquid-in-glass thermometer has no scale markings.
(i) Describe the procedure needed to determine
1. the position on the thermometer of the lower fixed point,
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2. the position on the thermometer of the upper fixed point.
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[3]
(ii) Explain why
1. the graduations marked on the thermometer between the fixed points are spaced equally,
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[1]
2. the expansion of the glass of the thermometer is ignored.
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[1]

A dolphin produces a sound wave in water of frequency 7800Hz.
Fig. 6.1 represents rarefactions of the sound wave travelling in the water and hitting the side of a wooden ship at an angle.

[Image_1: Fig. 6.1 depicting rarefactions and the direction of wave travel]

(a) State what is meant by a rarefaction.
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(b) On Fig. 6.1, two rarefactions A and B are labelled. The distance between rarefaction A and rarefaction B is 0.76m.
Determine
(i) the wavelength in water of the sound wave,
wavelength = ......................................................[1]
(ii) the time taken for the rarefaction at A to reach the point where rarefaction B is now positioned.
time = ......................................................[2]

(c) The sound wave passes from the water into the wood where the speed of sound is greater.
State what happens to
(i) the frequency,
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(ii) the wavelength.
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(d) On Fig. 6.1, sketch the positions in the wood of the three incomplete rarefactions. [2]

(a) The refractive index of a type of glass is 1.6.

Calculate the critical angle for light in this type of glass.

critical angle = ......................................................[3]

(b) A waterproof laser is immersed in water. Fig. 7.1 shows the laser shining light up towards the horizontal surface of the water.



Initially, the angle $\theta$ is much less than the critical angle for this light in water.

The laser moves and $\theta$ gradually increases until it is much greater than the critical angle.

Describe, for different angles of the laser, what happens to the light beam after it hits the surface.

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A metal sphere, mounted on an insulating plastic stand, is positively charged.

(a) State the name of the unit in which electric charge is measured.
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(b) A smaller metal sphere, also mounted on an insulating plastic stand, is uncharged.
This smaller sphere is moved close to the positively charged sphere. Fig. 8.1 shows the two spheres.


(i) On Fig. 8.1, draw the distribution of charge on the smaller sphere. [2]

(ii) An earthed metal wire is touched against the smaller metal sphere.

State and explain what happens to the charge on the smaller sphere.
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(c) Explain, in terms of their structures, why the metal wire is an electrical conductor but the plastic stand is an electrical insulator.
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(a) Place one tick in each row of the table to indicate one use of a thermistor and one use of a transistor.

[Table_1]

| | heat detector | light detector | magnetic field detector | rectifier | switch |
|-----------------|---------------|----------------|--------------------------|-----------|--------|
| thermistor | | | | | |
| transistor | | | | | |

[2]

(b) In Fig. 9.1, lamp A is not glowing brightly.



Suggest and explain what could be done to component B to make lamp A glow brightly.
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The output of an a.c. generator in a power station is 5000 V.
A transformer increases the voltage to 115000 V before the electrical power is transmitted to a distant town.

(a) State and explain, using a relevant equation, one advantage of transmitting electrical power at a high voltage.

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(b) The transformer contains two coils, the primary coil and the secondary coil.

(i) State the other main component of a transformer and the material from which it is made.
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(ii) State the component in the transformer to which the a.c. generator is connected.
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(iii) There are 400 turns on the primary coil of the transformer.
Calculate the number of turns on the secondary coil.

number of turns = ........................................................[2]

(c) Transformers within the town reduce the voltage to 230 V.
Suggest one reason for this.
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Uranium-238 and uranium-234 are radioactive isotopes of the element uranium. A uranium-238 nucleus is different from a uranium-234 nucleus but both decay by the emission of an $\alpha$-particle.

(a) (i) In terms of the particles in each, state how a nucleus of uranium-238 differs from a nucleus of uranium-234.
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(ii) Although the two nuclei are different, they are both nuclei of uranium.
State a property that makes these isotopes the same element.
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(b) When $\alpha$-particles pass through air, they are more strongly ionising than $\beta$-particles.
Suggest two reasons why this is so.
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(c) In an experiment, $\alpha$-particles are allowed to strike a thin gold foil in a vacuum.
Almost all the $\alpha$-particles pass straight through the gold undeflected. Only a very small number of $\alpha$-particles are deflected from their original path.
This result reveals certain features of the atoms of the gold.
State what is shown about atoms by the fact that
(i) most $\alpha$-particles pass straight through the gold undeflected,
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(ii) some $\alpha$-particles are deflected back the way they came.
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