Forces, Movement, Shape, and Momentum
4 marks · EasyA block is pulled along a rough, horizontal surface. The block experiences a friction force and is stretched by a spring attached to it.
Describe one effect of the friction force on the block as it moves along the surface.
The spring attached to the block is stretched. State what will happen to the shape of the spring when the block is released and explain your answer.
Name the type of force that causes the spring to return to its original shape.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) It slows down the block / opposes motion / causes it to stop.
(b) The spring will return to its original shape/length, because it is elastic and can recover its shape when the force is removed.
(c) Restoring force (or elastic force).
Common mistakes: Mixing up friction with air resistance; Stating the spring will stay stretched after release
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · States friction slows the block, opposes motion, or causes it to stop.
B1 (b) · 1 mark · States the spring returns to its original shape/length.
B1 (b) · 1 mark · Explains the spring is elastic/can recover after the force is removed.
B1 (c) · 1 mark · Names restoring force or elastic force.
Worked solution
(a) The friction force opposes the motion, so it slows down the block and can cause it to stop if it is large enough.
(b) When the block is released, the spring will return to its original shape or length, because it behaves elastically and can recover its shape after the force has been removed.
(c) The restoring force (or elastic force) causes the spring to return to its original shape.