A2 Waves and Fields Multiple Choice

Hey, I have a multiple choice question I am a bit stuck on...

A girl of mass 40kg stands on a roundabout 2.0m from the vertical axis as the roundabout rotates with a period of 2.0s. The horizontal force acting on the girl is approx: zero, 3.5x10^2N, 7.2x10^2N, 2.8x10^4N

Also, any tips for this exam because my teacher is a little bit worried of the multiple choice paper, and doesnt seem to teach us how to get them right...
:frown:

Thanks!

Reply 1

teachercol

SHe will travel a distance 2 x pi x2.0 m every 2.0s so you can work out her velocity

Then use F = m v^2 / r

Reply 2

Chris the Mathematician!

teachercol

SHe will travel a distance 2 x pi x2.0 m every 2.0s so you can work out her velocity

Then use F = m v^2 / r

Thanks, got the answer.
I just couldnt think of how to link the velocity to the numbers given!
:biggrin:

Reply 3

JBC10

I've just had the same question 12 years later, except period is 3.0s. I did initially do the V formula, but discontinued it when i got a strange answer. It never clicked for me to then try v in a different formula such of f =mv^2/r

Reply 4

Eimmanuel

Study Forum Helper

Original post by JBC10

As you have noticed that this is a more than 12 years old thread. It would be better that you start a new thread and refer to this thread in future.

There is more than one way of expressing centripetal force.

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