1. Motion, forces and energy

1.1 Physical quantities and measurement techniques

1.2 Motion

1.3 Mass and weight

1.4 Density

1.5.1 Effects of forces

1.5.2 Turning effect of forces

1.5.3 Centre of gravity

1.6 Momentum

1.7.1 Energy

1.7.2 Work

1.7.3 Energy resources

1.7.4 Power

1.8 Pressure

2. Thermal physics

2.1.1 States of matter

2.1.2 Particle model

2.1.3 Gases and the absolute scale of temperature

2.2.1 Thermal expansion of solids, liquids and gases

2.2.2 Specific heat capacity

2.2.3 Melting, boiling and evaporation

2.3.1 Conduction

2.3.2 Convection

2.3.3 Radiation

2.3.4 Consequences of thermal energy transfer

3. Waves

3.1 General properties of waves

3.2.1 Reflection of light

3.2.2 Refraction of light

3.2.3 Thin lenses

3.2.4 Dispersion of light

3.3 Electromagnetic spectrum

3.4 Sound

4. Electricity and magnetism

4.1 Simple phenomena of magnetism

4.2.1 Electric charge

4.2.2 Electric current

4.2.3 Electromotive force and potential difference

4.2.4 Resistance

4.2.5 Electrical energy and electrical power

4.3.1 Circuit diagrams and circuit components

4.3.2 Series and parallel circuits

4.3.3 Action and use of circuit components

4.4 Electrical safety

4.5.1 Electromagnetic induction

4.5.2 The a.c. generator

4.5.3 Magnetic effect of a current

4.5.4 Force on a current-carrying conductor

4.5.5 The d.c. motor

4.5.6 The transformer

5. Nuclear physics

5.1.1 The atom

5.1.2 The nucleus

5.2.1 Detection of radioactivity

5.2.2 The three types of nuclear emission

5.2.3 Radioactive decay

5.2.4 Half-life

5.2.5 Safety precautions

6. Space physics

6.1.1 The Earth

6.1.2 The Solar System

6.2.1 The Sun as a star

6.2.2 Stars

6.2.3 The Universe

IGCSE Physics Extended 1.6 Momentum Question Bank

[Maximum number: 1]

Which quantity is measured in newton seconds (Ns)?

impulse

moment

power

work done

[Maximum number: 4]

A rocket is stationary on the launchpad. At time t=0, the rocket engines are switched on and exhaust gases are ejected from the nozzles of the engines. The rocket accelerates upwards.

Fig. 1.1 shows how the acceleration of the rocket varies between time t=0 and time $t=t_{\mathrm{f}}$ .

Fig. 1.1

(a)

Some time later, the rocket is far from the Earth. The effect of the Earth's gravity on the motion of the rocket is insignificant. As the rocket accelerates, its momentum increases.

[ 4 ]

(i)

State the principle of the conservation of momentum.

[ 2 ]

(ii)

Explain how the principle of the conservation of momentum applies to the accelerating rocket and the exhaust gases.

[ 2 ]

[Maximum number: 2]

An aeroplane of mass $2.5 \times 10^{5} \mathrm{~kg}$ lands with a speed of $62 \mathrm{~m} / \mathrm{s}$ , on a horizontal runway at time t=0. The aeroplane decelerates uniformly as it travels along the runway in a straight line until it reaches a speed of $6.0 \mathrm{~m} / \mathrm{s}$ at $t=35 \mathrm{~s}$ .

(a)

Calculate:

[ 2 ]

(i)

the momentum of the aeroplane when its speed is $6.0 \mathrm{~m} / \mathrm{s}$ .

momentum =

[ 2 ]

[Maximum number: 7]

Fig. 1.1 shows an ice-hockey player moving on ice. He is preparing to hit the solid disc called a puck.

Fig. 1.1

The disc of mass 0.16 kg is moving horizontally across the surface of the ice at a speed of $15 \mathrm{~m} / \mathrm{s}$ .

(a)

Calculate the magnitude of the momentum of the disc.

magnitude of momentum =

[ 2 ]

(b)

The hockey player strikes the disc with his hockey stick and the momentum of the disc changes. The disc gains momentum of $3.0 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ at $45^{\circ}$ to the original direction of travel of the disc, as shown in Fig. 1.2.

Fig. 1.2 (view from above)

[ 5 ]

(i)

State the magnitude of the impulse exerted on the disc and the direction, in degrees, of the impulse relative to the original direction of travel.
magnitude of impulse =
direction of impulse: ${ }^{\circ}$ to original direction

[ 1 ]

(ii)

Determine the magnitude of the new momentum of the disc and its new direction relative to the original direction of travel by drawing a scale diagram.
direction of new momentum: ${ }^{\circ}$ to original direction

[ 4 ]

[Maximum number: 3]

Two blocks, A and B, are joined by a thin thread that passes over a frictionless pulley. Block A is at rest on a rough horizontal surface and block B is held at rest, just below the pulley.

Fig. 1.1 shows the thread hanging loose.

Fig. 1.1 (not to scale)

Block B is released and it falls vertically. The thread remains loose until block B has fallen a distance of 0.45 m .

The mass of block B is 0.50 kg .

(a)

The mass of block A is 2.0 kg.

When the thread tightens, it pulls on block A which moves to the right at a speed of $0.60 \mathrm{~m} / \mathrm{s}$ .

[ 3 ]

(i)

Calculate the impulse exerted on block A as it accelerates from rest to $0.60 \mathrm{~m} / \mathrm{s}$ .
impulse = [3]

[ 3 ]

[Maximum number: 5]

A girl holds a rubber ball out of a window of a tall building. The mass of the ball is 0.20 kg . The ball is at rest 10 m above a concrete path.

(a)

The girl releases the ball and it falls towards the path. The ball strikes the path and bounces vertically upwards.

Fig. 1.1 shows the ball falling towards the path.

Fig. 1.1

The speed of the ball immediately before it strikes the path is $14 \mathrm{~m} / \mathrm{s}$ .
The speed of the ball immediately after it strikes the path is $12 \mathrm{~m} / \mathrm{s}$ .

[ 5 ]

(i)

Show that the change in momentum of the ball when it bounces off the path is $5.2 \mathrm{~kg} \mathrm{~m} / \mathrm{s}$ .

[ 3 ]

(ii)

The ball is in contact with the path for 0.25 s .

Calculate the average resultant force on the ball when it is in contact with the path.
force = [2]
[Total: 9]

[ 2 ]

[Maximum number: 3]

Fig. 2.1 shows a dummy of mass 70 kg used in a crash test to investigate the safety of a new car.

Fig. 2.1

The car approaches a solid barrier at $20 \mathrm{~m} / \mathrm{s}$ . It crashes into the barrier and stops suddenly.

(a)

(i)

Calculate the momentum of the dummy immediately before the crash.

momentum =

[ 2 ]

(ii)

Determine the impulse that must be applied to the dummy to bring it to rest.
impulse =

[ 1 ]

[Maximum number: 6]

Fig. 2.1 shows a model fire engine. Its brakes are applied.

Fig. 2.1

0.80 kg of water is emitted in the jet every 6.0 s at a velocity of $0.72 \mathrm{~m} / \mathrm{s}$ relative to the model.

(a)

Calculate the change in momentum of the water that is ejected in 6.0 s .
momentum =

[ 2 ]

(b)

Calculate the magnitude of the force acting on the model because of the jet of water.
force =

[ 2 ]

(c)

The brakes of the model are released.

State and explain the direction of the acceleration of the model.
Statement

Explanation

[ 2 ]

[Maximum number: 1]

Fig. 2.1 is the top view of a small ship of mass $1.2 \times 10^{6} \mathrm{~kg}$ . The ship is moving slowly sideways at $0.040 \mathrm{~m} / \mathrm{s}$ as it comes in to dock.

Fig. 2.1

The ship hits the wooden pillars which move towards the dock wall.

(a)

The ship is in contact with the pillars for 0.30 s as it comes to rest.

Calculate the average force exerted on the side of the ship.

force =

(b)

Dock walls sometimes have the pillars replaced with rubber car tyres.

Explain how this reduces the possibility of damage when a boat docks.
[Total: 9]

[ 1 ]

(a)

Complete the definitions by giving the name of each quantity.
mass × acceleration =
force × time =

[ 2 ]

(b)

Fig. 2.2 shows a man using a golf club to hit a ball.

Fig. 2.2

The ball has a mass of 0.046 kg . The golf club is in contact with the ball for a duration of $5.0 \times 10^{-4} \mathrm{~s}$ and the ball leaves the golf club at a speed of $65 \mathrm{~m} / \mathrm{s}$ .

[ 2 ]

(i)

Calculate the momentum of the ball as it leaves the golf club.

momentum =

[ 2 ]

(ii)

Calculate the average resultant force acting on the ball while it is in contact with the golf club.

average force =

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