Forces & Their EffectsOxford AQA IGCSE Physics: Topic test

20 questions, 54 marks

Oxford AQA IGCSE Physics

Forces & Their Effects topic test

Total 54 marks

Name

Class

Date

1
A warehouse operator uses an electric forklift truck to lift a wooden pallet stacked with boxes, of total mass 250 kg, from the warehouse floor onto a storage shelf 2.4 m above the ground, raising it at a slow and constant speed.
(a)
Which of the following is a non-contact force acting on the pallet as it is lifted?
[1 mark]
AThe weight of the pallet
BThe normal contact force from the forks
CFriction between the pallet and the forks
DThe push force applied by the forklift's hydraulic forks
(b)
As the pallet rises, which of the following quantities is a vector?
[1 mark]
AThe speed of the pallet
BThe weight of the pallet
CThe mass of the pallet
DThe time taken to lift the pallet
(c)
Calculate the weight of the pallet and its boxes as it is lifted, taking the gravitational field strength to be 10 N/kg. Give the unit.
[2 marks]
Total for question 1: 4 marks
2
A delivery cyclist sets off from rest outside a depot and accelerates steadily for the first 10 s of her journey, covering 40 m. She then rides at a steady speed for a further 20 s, covering 150 m, before turning into a driveway.
(a)
Which statement correctly distinguishes velocity from speed?
[1 mark]
AVelocity and speed always have the same numerical value
BSpeed includes a direction but velocity does not
CVelocity includes a direction but speed does not
DVelocity can only be measured for objects moving in a straight line
(b)
Which calculation gives the cyclist's average speed for the complete 30 s journey?
[1 mark]
A40 divided by 10
B150 divided by 20
C190 divided by 30
D190 divided by 10
(c)
Calculate the cyclist's average speed during the first 10 s of her journey, while she is accelerating from rest.
[2 marks]
Total for question 2: 4 marks
3
Two tugboats are used to tow a barge of mass 5000 kg along a canal. One tugboat pulls with a force of 3000 N forwards, while the second tugboat pulls with a force of 1200 N forwards in the same direction. The water and canal walls provide a resistive force of 800 N acting backwards on the barge.
(a)
Calculate the resultant force acting on the barge, and state the direction in which it acts.
[3 marks]
(b)
Calculate the acceleration of the barge produced by this resultant force, and explain what would happen to the barge's motion if the two tugboats' forces became exactly equal in size to the resistive force.
[4 marks]
Total for question 3: 7 marks
4
A car safety research team crash-tests a car of mass 1200 kg travelling at 12 m/s into a fixed barrier. The car is fitted with a crumple zone at the front and an airbag that inflates on impact, both designed to protect the driver during the collision.
(a)
Calculate the momentum of the car just before the collision, and explain, using the idea of the rate of change of momentum, why fitting a crumple zone reduces the force experienced by the driver during the crash.
[6 marks]
(b)
In a separate test, the same car, still moving at 12 m/s, collides with a stationary car of mass 800 kg and the two cars lock together and move off with a common velocity. Calculate this common velocity using conservation of momentum, and explain how the airbag further reduces the risk of injury to the driver during a collision.
[6 marks]
Total for question 4: 12 marks
5
A bus travels along a wet urban road at a steady 15 m/s. The bus driver, who is tired after a long shift, sees a pedestrian step into the road ahead and must react before applying the brakes to bring the bus safely to a stop.
(a)
Which of the following would most directly increase the driver's thinking distance in this situation?
[1 mark]
AThe wet road surface
BThe driver's tiredness increasing her reaction time
CWorn brake pads on the bus
DThe mass of passengers on the bus
(b)
Once the driver applies the brakes, which statement best explains why the bus's braking distance is likely to be greater on the wet road than on a dry road?
[1 mark]
AThe wet road reduces friction between the tyres and the road, so a greater distance is needed to stop
BThe wet road increases the driver's reaction time
CThe wet road increases the bus's kinetic energy
DThe wet road increases the mass of the bus
(c)
State what is meant by the 'stopping distance' of the bus, and explain, in terms of energy, why braking heats the brakes.
[2 marks]
Total for question 5: 4 marks
6
An engineering student tests a scale-model cargo pod, released from a hovering drone at height, fitted with a small stabilising parachute that opens immediately on release. The pod falls vertically through still air towards a padded landing area.
(a)
Immediately after release, before the pod reaches terminal velocity, which statement correctly describes the forces acting on it?
[1 mark]
AAir resistance is greater than weight, so the pod decelerates
BAir resistance equals weight, so the pod falls at constant velocity
CThere are no forces acting on the falling pod
DWeight is greater than air resistance, so the pod accelerates downwards
(b)
As the pod continues to fall, air resistance increases until the pod reaches a constant speed called its terminal velocity. Which statement correctly describes the forces at terminal velocity?
[1 mark]
AWeight is greater than air resistance
BAir resistance is greater than weight
CThere is a resultant force acting downwards
DWeight and air resistance are equal in size, so the resultant force is zero
(c)
Explain, in terms of the forces acting on it, why the stabilising parachute causes the pod to reach a lower terminal velocity than it would without a parachute.
[2 marks]
Total for question 6: 4 marks
7
A furniture designer is testing the stability of a new bookcase, a tall symmetrical unit standing on a level floor. She wants to check where its centre of mass lies before it is filled with books, and then investigates how filling it with heavy books changes its stability.
(a)
State what is meant by the 'centre of mass' of the bookcase, and state where the centre of mass of the empty bookcase lies, given that it is a symmetrical shape.
[3 marks]
(b)
Describe how the designer could find the centre of mass of an irregularly shaped offcut of the bookcase's shelving material using a plumb line, and explain why filling the top shelves of the bookcase with heavy books makes it less stable.
[4 marks]
Total for question 7: 7 marks
8
A mobile crane has a horizontal jib that can pivot about a fixed point. To lift a steel girder of weight 6000 N, the crane operator hangs the girder from a hook 8 m from the pivot, and the crane's fixed counterweight of weight 4000 N sits on the opposite side of the jib at a distance that can be adjusted before each lift.
(a)
Calculate the distance from the pivot at which the counterweight must be placed so that the jib is exactly balanced with the girder attached, and state the principle you have used.
[6 marks]
(b)
Explain, using the idea of centre of mass and moments, what would happen to the stability of the crane if the operator failed to move the counterweight far enough from the pivot before lifting the girder, and explain how the long jib itself acts as a lever to help lift the heavy girder.
[6 marks]
Total for question 8: 12 marks

End of questions