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AS Physics Mechanics Question

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I know that the answer is A, but please could someone explain why the graphs for kinetic energy and momentum look like that? I don't quite understand why the graph for kinetic energy is a curve. Thank you :smile:
Reply 1
If you've got a constant force acting on the object, it will have a constant acceleration (can you say why?). So you can use the suvat equations to analyse its motion. Can you use v = u + at to see why the momentum graph in A must be correct?

So if we are happy with the idea that the velocity is increasing at a constant rate, either because of v = u + at or becasue of the momentum graph, you can think about what would happen with kinetic energy. If KE = 1/2mv2, does the square in that equation help to explain why the KE graph must be curved? (In fact, you can be far more specific than just saying it is curved, we can say what kind of curve it is.)
For the second graph, you can also think about it because of the fact force = rate of change of momentum, so for a constant force, the graph of momentum against time will be a straight line of constant gradient.

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