Work energy and momentum

Question 1

Describe an experiment to check whether the speed of the rising mass is constant.

Answer 1

mark out (equal) distances along height being raised (1)
measure time taken to travel each of these distances (1)
times should be equal (1)

Question 2

Describe how the speed of the trolley, just before it collides with the block may be
measured experimentally

Answer 2

when using light gates
place piece of card on trolley of measured length (1)
card obscures light gate just before trolley strikes block (1)
calculate speed from length of card/time obscured

Question 3

What is newtons first law

Answer 3

A moving object will continue moving as long as no unbalanced forces act on it

Question 4

State what measurements would need to be made to investigate the conservation of
energy in a mass and trolley experiment. How would these measurements be used?

Answer 4

masses of trolley and falling mass
distance mass falls (or trolley moves) and time taken to
fall (or speed).calculate loss of gravitational pot. energy of falling mass (mgh)
calculate speed of trolley (as mass hits floor). Compare the loss in GPE to gain in KE

Question 5

Explain why a raindrop falling vertically through still air reaches a constant velocity. You
may be awarded marks for the quality of written communication in your answer.

Answer 5

weight/gravity causes raindrop to accelerate/move faster (initially)
resistive forces/friction increase(s) with speed
resistive force (eventually) equals weight
[or upward forces equal downward forces]
resultant force is now zero

Question 6

State, in words, the relationship between the force acting on a body and the
momentum of the body.

Answer 6

force is equal to (or proportional to) rate of change of momentum