Question
A mass m is attached to a cord passing through a small hole in a frictionless, horizontal surface. The mass is initially orbiting with speed vi in a circle of radius ri. The cord is then slowly pulled from below, and the radius of the circle decreases to r. (Use r_i for ri, v_i for vi, m, and r as appropriate in your equations below.)
(a) What is the speed of the mass when the radius is r?
(b) Find the tension in the cord as a function of r
(c) How much work W is done in moving m from ri to r? (Note: The tension depends on r.)
Do you just use conservation of energy for this? Is it just rotational energy?
(a) What is the speed of the mass when the radius is r?
(b) Find the tension in the cord as a function of r
(c) How much work W is done in moving m from ri to r? (Note: The tension depends on r.)
Do you just use conservation of energy for this? Is it just rotational energy?
Answers
bobpursley
use conservation of angular momentum, it is easier. Angularmomentum=Vi/ri * mi
But you can use energy if you wish.
But you can use energy if you wish.