5.2 Contact and non-contact forces
9 exam questions worth 21 marks. Write your answer, open the mark scheme, then give yourself the marks you earned. Your answers are saved on this device.
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Which of these is a non-contact force?
Choose one answer.
Correct Not quite: the answer is Gravitational force
Mark scheme
C: Gravitational force
Model answer
Gravitational force (C).
A force is measured in:
Choose one answer.
Correct Not quite: the answer is Newtons
Mark scheme
B: Newtons
Model answer
Newtons (B).
State the difference between a contact force and a non-contact force. Give one example of each.
Mark scheme
contact force acts when objects are touching (1); example: any from friction, tension, air resistance, normal contact force (1); non-contact force acts between objects without touching (1); example: any from gravitational, magnetic, electrostatic (1)
Model answer
A contact force acts when two objects are touching, for example friction. A non-contact force acts when the objects are not touching, for example the gravitational force between the Earth and the Moon.
A book is at rest on a table. Name the two forces acting on the book and state the direction of each.
Mark scheme
weight / gravity (1); acts downwards (1); normal contact force from the table (1); acts upwards (1)
Model answer
The weight of the book acts downwards, and the normal contact force from the table acts upwards.
State what happens to the air resistance on a falling object as its speed increases.
Mark scheme
it increases
Model answer
The air resistance increases.
Explain why rubbing your hands together makes them feel warmer.
Mark scheme
friction acts between the hands (1); transferring energy to the thermal store / the hands heat up (1)
Model answer
Friction between your hands does work, which transfers energy to the thermal store of your hands, so they warm up.
A student says that a magnet can only attract objects when it touches them. Explain why this is wrong.
Mark scheme
magnetic force is a non-contact force (1); it acts through a magnetic field, so can attract objects at a distance (1)
Model answer
The magnetic force is a non-contact force. It acts through the magnetic field, so objects can be attracted without touching.
Describe two forces that act on a car being towed along a road at a constant speed.
Mark scheme
tension in the tow rope (1); acts forwards (1); friction / air resistance (1); acts backwards / opposite to the motion (1)
Model answer
The tension in the tow rope pulls the car forwards. Friction and air resistance act backwards, opposite to the motion.
Give two ways of reducing friction between the moving parts of a machine.
Mark scheme
lubricate with oil / grease (1); use smoother surfaces / ball bearings / reduce the force pressing the surfaces together (1)
Model answer
Put oil or grease between the moving parts, and make the surfaces smoother.
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