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Circular motion

There's a question in one of the A2 Physics papers...

It says a ball has velocity 40m/s calculate the radius of the circular motion.

No other information is given. No mass, no time period, no acceleration. NOTHING.

Anyways, I'm a god damned brilliant Physicist and I can't figure it so help me if you will.

Thanks you guys and have a good new year.

Come on Cambridge!

Reply 1

Mohit_C

Well, if you say you're a good Physicist, maybe my approach to this question makes no sense but here I go.
w=2pi/T=V/r

Let the T= 1 second.
So in 1 second it travels 40 metres.
so the circumeference is 40 metres.
Circumference = 2pir
so 40=2pir
r=20/pi?

Reply 2

Morbo

You can't work out the radius of circular motion solely from the speed.

v = r*w - where v=speed, r=radius of circular motion, w=angular frequency of the motion

We don't know the angular frequency, or anything else to work it out from, so we can't know the radius! It could be a ball in a very small circle with a large angular frequency, or it could be a ball in a very large circle with a small angular frequency.

Reply 3

Mohit_C

Yes, Worzo is right. I made the assumption that it took 1 second to go around the circle, which I pretty much doubt it. Can you tell us from which paper that is from?