# Help with ratios of velocity and centripetal acceleration

1. Apr 20, 2004

### wikidrox

I really need some help with this question. Until now this is the first question I have ever seen like this and I am getting marked on it. here it is:

Two racing cars of masses M1 and M2 are moving in circles of radii R1 and R2. Their speeds are such that they each make a complete circle in the same length of time.

a) What is the ratio of the angular speed (measured in degrees of arc per second) of the first car to that of the second car?

b) What is the ratio of speed (measured in meters per second) of the first car to that of the second?

C) what is the ratio of centripetal acceleration of the first car to that of the second?

d) What is the ratio of the centripetal force acting on the first car to that acting on the second?

I have included the diagram, but it has a low quality. But it appears that R2 = 2R1 if that helps. I don't know how to do this if no values are involved.

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2. Apr 20, 2004

What's the difference between a letter and a number? A letter's easier to write!

I can't read your diagram, so I'll just give you a few hints.

A) They each make a complete circle in the same amount of time. So they're completing a full revolution in the same amount of time. What's angular velocity again?

w = 2pi/T

Hm... Same time...

B) v = wr

Combine this equation with the result from part 1.

C) a = r*w^2

Combine this equation with the result from part 1.

D) I think you get the idea by now.