Solving the Water Bucket Problem: Finding Vmin with Given Parameters"

[black_hole]

Homework Statement

Is it possible to whirl a bucket of water fast enough in a vertical circle so that the water won't fall out at the top? If the distance from your shoulder to the bottom of the bucket is 0.77 m and the water has a mass of 5.05 kg, what is the minimum speed to whirl the pail?

Homework Equations

The Attempt at a Solution

The answer is yes, but to find Vmin?

I know r = .77m, m = 5.05kg (although shouldn't I have been given the bucket mass also?), so i was thinking

Fnet = -Fg + Ft = mV^2/r

but how do i find Ft, or is there no Ft? explain

 

[Mindscrape]

You don't need the mass of the bucket because you're concerned about the water. What do you mean by Ft? You're looking for the sum of the forces to come to equilibrium.

 

[black_hole]

By Ft I mean tension force exerted by my arm. I didn't think there was any Fn (normal force), right?

 

[Redbelly98]

If the bucket is swinging "just fast enough", your arm exerts no force on it at the top of the circle. With that information you can solve your equation,

Fnet = -Fg + Ft = mV^2/r