Motion, Forces and EnergyCambridge IGCSE Physics: Topic test

20 questions, 54 marks

Cambridge IGCSE Physics

Motion, Forces and Energy topic test

Total 54 marks

Name

Class

Date

1
An engineer weighs a rectangular brass block and measures its dimensions with a ruler, finding it to be 5.0 cm long, 4.0 cm wide and 2.0 cm high, with a mass of 344 g.
(a)
What is the volume of the brass block?
[1 mark]
A40 cm3
B11 cm3
C70 cm3
D344 cm3
(b)
What is the density of the brass block?
[1 mark]
A0.12 g/cm3
B8.6 g/cm3
C40 g/cm3
D17.2 g/cm3
(c)
Describe how the engineer could find the density of an irregularly shaped stone that sinks in water, using a measuring cylinder rather than a ruler.
[2 marks]
Total for question 1: 4 marks
2
A worker loads a wheelbarrow so that the total load of 250 N acts at a horizontal distance of 0.30 m from the wheel (the pivot). The worker lifts the handles, which are 1.20 m from the wheel, to wheel the load away.
(a)
What is the moment of the load about the wheel?
[1 mark]
A300 Nm
B833 Nm
C75 Nm
D0.0012 Nm
(b)
What minimum downward force must the worker apply at the handles, 1.20 m from the wheel, to just lift the load, taking moments about the wheel?
[1 mark]
A75 N
B300 N
C90 N
D62.5 N
(c)
State the principle of moments and explain how it applies at the instant the wheelbarrow is about to lift off the ground.
[2 marks]
Total for question 2: 4 marks
3
In a laboratory, trolley A, of mass 2.0 kg, moves at 3.0 m/s along a frictionless track and collides with stationary trolley B, of mass 1.0 kg. The trolleys stick together and move off with a common velocity.
(a)
Calculate the momentum of trolley A before the collision, and use the principle of conservation of momentum to determine the common velocity of the trolleys immediately after the collision.
[3 marks]
(b)
Calculate the kinetic energy of trolley A before the collision and the total kinetic energy of the trolleys immediately after the collision, and use your values to state, with a reason, whether the collision is elastic.
[4 marks]
Total for question 3: 7 marks
4
A warehouse crane lifts a crate of mass 150 kg from the ground through a vertical height of 8.0 m in a time of 12 s, at a constant slow speed. Take the gravitational field strength as 9.8 N/kg.
(a)
Calculate the weight of the crate, the work done by the crane in lifting it, and the useful power output of the crane. State the energy store that increases as the crate rises, and describe the overall energy transfer taking place as the crane's motor lifts the crate.
[6 marks]
(b)
The crate is then lowered back to the ground using the crane's brake to control its descent over the same 8.0 m, reaching a speed of 4.0 m/s just before landing. Calculate the kinetic energy of the crate at this speed and compare it with the loss in its gravitational potential energy over the descent, explaining, in terms of conservation of energy, why the two values differ.
[6 marks]
Total for question 4: 12 marks
5
A delivery company loads a crate of mass 45 kg onto a small cargo aircraft. On Earth the gravitational field strength is 9.8 N/kg. The aircraft later delivers identical equipment to a research base on the Moon, where the gravitational field strength is 1.6 N/kg.
(a)
What is the weight of the 45 kg crate on Earth?
[1 mark]
A441 N
B72 N
C45 N
D4.6 N
(b)
What is the mass of the crate when it is on the Moon?
[1 mark]
A7.2 kg
B45 kg
C72 kg
D28.1 kg
(c)
Explain why the crate's weight is different on the Moon from its weight on Earth, even though its mass is unchanged.
[2 marks]
Total for question 5: 4 marks
6
A forklift truck applies a steady resultant (net) force of 900 N to a pallet of goods of mass 300 kg, initially at rest on a warehouse floor, accelerating it forward.
(a)
What is the acceleration of the pallet?
[1 mark]
A0.33 m/s2
B270000 m/s2
C3.0 m/s2
D600 m/s2
(b)
The forklift then switches off its motor while still gripping the pallet, so that the resultant force on the pallet becomes zero. Assuming no friction, what happens to the pallet's motion?
[1 mark]
AIt decelerates to rest immediately
BIt continues to accelerate
CIt reverses direction
DIt continues moving at constant velocity in a straight line
(c)
In practice, friction between the pallet and the floor is not zero. Describe what solid friction is, and state one effect it would have on the pallet's motion once the forklift's motor is switched off.
[2 marks]
Total for question 6: 4 marks
7
A concrete block of weight 1800 N rests on the ground, with a base of area 1.5 m2 in contact with the ground. Separately, a diver descends to a depth of 12 m below the surface of the sea, where the density of seawater is 1030 kg/m3 and the gravitational field strength is 9.8 N/kg.
(a)
Calculate the pressure the concrete block exerts on the ground.
[3 marks]
(b)
Calculate the increase in pressure due to the sea water at a depth of 12 m below the surface, and state what this increase in pressure must be added to in order to find the total pressure at that depth.
[4 marks]
Total for question 7: 7 marks
8
A small wind turbine transfers energy from moving air at a rate (power) of 45000 W. The turbine's generator produces a useful electrical power output of 13500 W.
(a)
Calculate the efficiency of the wind turbine as a percentage, and describe, using the idea of conservation of energy, what happens to the energy that is not transferred to useful electrical output.
[6 marks]
(b)
The energy company operating the turbine is comparing it with a small coal-fired power station of similar electrical power output. Describe one advantage and one disadvantage of the wind turbine compared with the coal-fired power station, and state the original source of the energy used by each method.
[6 marks]
Total for question 8: 12 marks

End of questions