Centripetal Force Homework: Solving for F with F = ma

[jensson]

Homework Statement

I did an expirement in my physics lab on centripetal force. I'm doing the calculations and right now I am calculating the centripetal force using equation: F= (mass)(angular speed squared)(average radius). My answers are coming out to be huge numbers.

ex: (148.8g)(52.70 rev/s)^2(5.494 cm) = 2270217

I'm not even sure what units this converts too.

If I convert g to kilegrams and revolutions/second times 2pi (in radians) then convert cm to meters I get:

(0.1488 kg) (331^2)(0.05494 m ) = 895.7 N

but this is too big as well. what am I doing wrong??

 

[ehild]

You need the angular speed in the formula. How is it defined? ehild

 

[jensson]

the equation for angular speed we're using is 2pi (n)/elapsed time

n is revolutions

I think I need to convert this to m/s?

 

[jensson]

is 896.2 N reasonable?

 

[ehild]

is 896.2 N reasonable?

almost... It is 890.62 N. One zero is missing.

ehild

 

[jensson]

can you please show me how you got that? because when I put

(0.1488) (331.1^2) (0.05494) that comes out to 896.2 N

 

[ehild]

You are right, I misread something on my calculator.

ehild

 

[jensson]

that seems like a lot of Newtons! This was an experiment in class with a little motor driven rotator.