An object with a mass of 6 kg6kg is revolving around a point at a distance of 8 m8m. If the object is making revolutions at a frequency of 2 Hz2Hz, what is the centripetal force acting on the object?

1 Answer
Feb 17, 2016

I found: 7580N7580N

Explanation:

Centripetal Force is:
F_c=mv^2/rFc=mv2r
where:
m=m=mass;
v=v= linear velocity;
r=r= radius.

The frequency tells us the number of complete revolutions in one seconds (here 2 revolutions).
We can ask ourselves what will be the Angular Velocity omegaω of our object, i.e., a kind of "curved" velocity involving not linear distance but angle described in time!

So we get:

omega="angle"/"time"=(2pi)/Tω=angletime=2πT

Where TT will be the Period of time for a complete revolution (time to describe 2pi2π radians).

The good thing is that the period is connected to frequency as "frequency"=nu=1/Tfrequency=ν=1T
and also the angular velocity can be changed into linear velocity simply considering at what distance from the center you are travelling....(basically, you include the radius)!!!!
so:
v=omega*rv=ωr

in our case we get (collecting all our stuff):

F_c=m(omega*r)^2/r=momega^2r=m(2pinu)^2r=6*(2*3.14*2)^2*8~~7580NFc=m(ωr)2r=mω2r=m(2πν)2r=6(23.142)287580N