Grade_X Physics_P2

Q1. Fig. 1.1 is the speed-time graph for an ice skater.

(a) Explain what is meant by deceleration.

….............................................................................................[1]

(b) Use Fig. 1.1 to determine

(i) the distance travelled between times t = 3.0 s and t = 6.0 s,

distance = .......................... [1.5]

(ii) the deceleration between times t = 3.0 s and t = 6.0 s.

deceleration = ............................. [1.5]

(c)

(i) State what happens to the size of the deceleration after time t = 6.0 s.

................................................................................................[1]

(ii) State what happens to the resultant force on the skater after time t = 6.0 s.

................................................................................................[1]

Total: [6]

Q2. (a) State the two conditions required for the equilibrium of a body acted upon by a number of forces.

1..................................................................................................

2. ............................................................................................[2]

Fig. 2.1 shows a diagram of an arm with the hand holding a weight of 120 N.

The 20 N force is the weight of the forearm, acting at its centre of mass. F is the force in the muscle of the upper arm. P is the point in the elbow about which the arm pivots. The distances of the forces from point P are shown.

(i) By taking moments about point P, calculate the force F.

force F = ...................[2]

(ii) A force acts on the forearm at point P. Calculate this force and state its direction.

force = ..................................

direction = .......................[2]

[Total: 6]

Q3. Fig. 3.1 shows a pond that is kept at a constant depth by a pressure-operated valve in the base.

(a) The pond is kept at a depth of 2.0 m. The density of water is 1000 kg/m³.

Calculate the water pressure on the valve.

pressure =…………………….. [1.5]

(b) The force required to open the valve is 50 N. The valve will open when the water depth reaches 2.0 m.

Calculate the area of the valve.

area = ……………………….. [1.5]

(c) The water supply is turned off and the valve is held open so that water drains out through the valve.

State the energy changes of the water that occur as the depth of the water drops from 2.0 m to zero.

............................................................................................... [1]

Total [4]

Q4. Water is stored in a reservoir at an average vertical height of 350 m above the turbines of a hydroelectric power station.

During a 7.0 hour period, 1.8 × 10⁶ m³ of water flows down from the reservoir to the turbines.

(a) The density of water is 1000 kg / m³.

For this 7.0 hour period, calculate

(i) the mass of water that flows from the reservoir to the turbines,

mass = .................................................. [1.5]

(ii) the gravitational potential energy transformed as the water flows to the turbines,

energy = .................................................. [1.5]

(iii) the maximum possible average output power.

power = .................................................. [2]

(b) A hydroelectric power station generates electricity from a renewable energy source.

(i) Explain what is meant, in this context, by renewable.

................................................................................................[1]

(ii) State two other renewable energy sources.

1. …….……..............................................................................

2. …….……..................................................................... ....[1]

[Total: 07]

Q5. Fig. 5.1 shows a ray of light, PQRS, passing along a simple optical fibre.

(a) What is the angle between the ray PQ and the ray RS.

angle = ...................[0.5]

(b) Explain why the ray PQ does not leave the fibre at Q.

................................................................................................[1]

(c) Another ray TQ also strikes the surface at Q.

The refractive index of the glass is 1.50.

(i) Calculate the critical angle for this glass.

critical angle = ................[2]

(ii) Explain why the ray TQ leaves the fibre.

...............................................................................................[1]

(d) The light waves travelling towards Q have a frequency of 4x10¹⁴Hz and a wavelength of 5x10^–7 m.

(ii) Calculate the speed of these waves in the glass.

speed = ......................[1.5]

[Total: 6]

Q6. (a) State the range of frequencies of sound which can be heard by a healthy human ear.

............................................................................................ [0.5]

(b) Compressions and rarefactions occur along the path of sound waves.

State, in terms of the behaviour of molecules, what is meant by

(i) a compression,

....................................................................................................

(ii) a rarefaction.

..............................................................................................

[1]

(c) State the effect on what is heard by a listener when there is

(i) an increase in the amplitude of a sound,

............................................................................................ [0.5]

(ii) a decrease in the wavelength of a sound.

............................................................................................ [0.5]

(d) A student carries out an experiment to find the speed of sound in air.

He stands facing a high cliff and shouts. He hears the echo 1.9 s later.

He then walks 250 m further away from the cliff and shouts again, hearing the echo 3.5 s later.

Calculate the speed of sound given by this experiment.

speed = .................................................. [2.5]

[Total: 5]

Q7. A plastic rod is rubbed with a cloth and becomes negatively charged.

(a) Explain how the rod becomes negatively charged when rubbed with a cloth.

………………………………………………………………………………… [0.5]

(b) An uncharged metal-coated sphere hangs from an insulating thread. The sphere is brought near to the rod. The sphere is attracted to the rod, as shown in Fig. 7.1.

(i) Describe and explain what happens to the free electrons in the metal-coated sphere as it approaches the rod.

…………………………………………………………………………………....[1]

(ii) Draw a sphere on the paper to show how charge is distributed on the sphere. [1]

(iii) Explain why the uncharged sphere is attracted to the negatively-charged rod.

…………………………………………………………………………………... [1]

(c) With the charged rod still close, point X on the metal-coated sphere is earthed.

(i) State what is meant by earthing the sphere.

………………………………………………………………………………… [0.5]

(ii) Describe and explain what happens to the free electrons in the metal-coated sphere as it is earthed.

…………………………………………………………………………………... [1]

(iii) Draw a sphere on the paper to show how the charge is now distributed on the sphere. [1]

Total [06]