A bucket of mass 1.60 kg is whirled in a vertical circle of radius 1.00 m.

[fineztpaki]

Homework Statement

A bucket of mass 1.60 kg is whirled in a vertical circle of radius 1.00 m. At the lowest point of its motion the tension in the rope supporting the bucket is 25.0 N.
(a) Find the speed of the bucket.
(b) How fast must the bucket move at the top of the circle so that the rope does not go slack?

The Attempt at a Solution

I figured out A, the speed of the bucket to be 2.42 m/s but i don't understand how to find B.. can someone help please?

 

[Doc Al]

When the rope just goes slack what happens to its tension?

 

[fineztpaki]

the tension decreases?

 

[Doc Al]

the tension decreases?

To what value?

 

[fineztpaki]

less than 25?

 

[fineztpaki]

Is there any formula i would be able to use to solve this?

 

[Doc Al]

If there's any tension in the rope, it's not slack. The only formula you need is Newton's 2nd law.

 

[fineztpaki]

How do I get speed, or velocity (m/s) from that?
The answer is supposed to be in m/s ... I'm still confused

 

[Doc Al]

You solve part (b) the same basic way you solved part (a). What forces act on the bucket? Apply Newton's 2nd law. The differences: The bucket is at the top instead of the bottom. (What does that change?) And the tension is different. (What must it be just as the rope goes slack?)

Once you set up your equation you solve for v just like you did in part (a).

 

[fineztpaki]

3.13

 

[fineztpaki]

alright got it! thanks!

 

[Doc Al]

3.13

Yep. In m/s.