Your friend ties a 5.00kg rock

Question

to a string and swings it in a horizontal circle with a radius of 2.00m. She knows that the string will break if 55.0N of force is applied to it.

How fast can the rock move before the string breaks?

How long does it take the rock to make one revolution at this speed?

What is the period of revolution for the rock?

Answer 1

F = mv²/r, v = √(Fr/m) = √(55N·2m/5kg) = 4.69 m/s.

Time T of one rotation: T = 2πr/v = 2π·2m/4.69m/s = 2.63 s

This is period of rotation of rock>