9702/Oct Nov/11/2015/Q7

One of the equations of uniformly accelerated motion is shown.

s = ut + ½ at²

Apparatus is arranged to record the time t taken for a marble to fall between two light gates

connected to timers. The marble touches the stop before it is released. The vertical distance s

between the light gates is measured.

Which graph does not show a correct relationship when light gate 2 moves up to light gate 1
which is fixed?

Solution:
Answer: C

Choice A: from the formula s = ut + ½ at² , we know s ∝ t²  , so choice A is correct.

Choice B: we can derive the formula of s/t = u + ½ at. s/t ∝ t , so choice B is correct.

Choice D: The gravitational acceleration is always constant. So choice D is correct.

Choice C:
We can derive the formula of
ut = s – ½ at²

u = s/t – ½ at

So u = 0 at all the time is doesn't make sense.

Reference: PYQ - Oct/Nov 2015 Paper 11 Q7