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 1.7.4 Power Question Bank

1.7.4.1—Power as work done per unit time or

(a)

The bicycle has a motor with an electrical input power of 250 W .

Calculate the time for which the battery can power the bicycle.

time =..........................................................

[ 2 ]

[Maximum number: 5]

Fig. 2.1 shows a conveyor belt transporting a package to a raised platform. The belt is driven by a motor.

Fig. 2.1

(a)

The package is raised through the vertical height of 2.4 m in 4.4 s .

Calculate the power needed to raise the package.
power =

[ 2 ]

(b)

Assume that the power available to raise packages is constant. A package of mass greater than 36 kg is raised through the same height.

Suggest and explain the effect of this increase in mass on the operation of the conveyer belt.

[ 3 ]

[Maximum number: 5]

Fig. 2.1 shows a conveyor belt transporting a package to a raised platform. The belt is driven by a motor.

Fig. 2.1

(a)

The package is raised through the vertical height of 2.4 m in 4.4 s .

Calculate the power needed to raise the package.
power =

[ 2 ]

(b)

[ 3 ]

[Maximum number: 7]

Fig. 2.1 shows a simplified version of a 'gravity lamp'. This apparatus is used to light a light-emitting diode (LED) without mains electricity.

Fig. 2.1

The load of 12 kg is raised to a height of 1.7 m above the ground. The load is connected to a pulley system. The time taken for the load to fall to the ground is 1200 seconds. The load falls at constant speed. The generator is connected to an LED.

(a)

Calculate the rate of transfer of gravitational potential energy as the load falls to the ground.

rate of transfer of gravitational potential energy =

[Maximum number: 1]

Four electric motors do the same quantity of work when they lift a weight of 10 N through the same distance.

The times taken by each motor to lift the weight are shown.
What is the time taken by the motor which produces the most power?

1.5 s

6.0 s

15 s

60 s

[Maximum number: 3]

Water is held behind a dam in a hydroelectric power scheme.

(a)

The water is released from the dam and falls a vertical height of 410 m at a rate of $480 \mathrm{~kg} / \mathrm{s}$ .

[ 3 ]

(i)

Calculate the rate at which energy is transferred by the falling water.

rate of energy transfer =

[ 3 ]

(a)

A wind turbine has a maximum output power of 1.8 MW . The turbine operates at maximum power for 4.0 h .

[ 2 ]

(i)

Calculate the energy produced by the wind turbine operating at maximum power for 4.0 h . Give your answer in kWh.

energy = kWh [2]

[ 2 ]

[Maximum number: 1]

A boy takes 0.60 s to lift a book of mass 0.60 kg from the top of a desk and place it on a shelf. The top of the desk is 0.80 m above the floor, and the shelf is 1.7 m above the floor. The gravitational field strength is $10 \mathrm{~N} / \mathrm{kg}$ .

Which power does the boy develop?

$0.9 \mathrm{~W}$

1.7 W

9.0 W

$17 \mathrm{~W}$

[Maximum number: 1]

A man can either take an escalator or a lift to travel up between two floors in a hotel.

escalator

lift

The escalator takes 20 seconds to carry the man between the two floors. The useful work done against gravity is W. The useful power developed is P.

The lift takes 30 seconds to carry the same man between the same two floors.
How much useful work against gravity is done by the lift, and how much useful power is developed by the lift?

useful work

done against

gravity by lift

useful power

developed by lift

more than W

less than P

more than W

less than P

[Maximum number: 1]

A motor of power P exerts a force F on an object. The object moves a distance d during the time t that the force acts.

Which equation is used to calculate the time t ?

$t=\frac{F}{P d}$

$t=\frac{F d}{P}$

$t=\frac{P d}{F}$

$t=\frac{P}{F d}$

0 selected

Question 1

Question 1(b)

Question 2

Question 2(b)

Question 2(d)

Question 2

Question 2(b)

Question 2(d)

Question 2

Question 2(a)

Question 7

Question 2

Question 2(b)

Question 2(b)(i)

Question 3

Question 3(b)

Question 3(b)(ii)

Question 9

Question 9

Question 9