A curling stone of mass m is thrown with at initial velocity v, slows down and s
ID: 1545621 • Letter: A
Question
A curling stone of mass m is thrown with at initial velocity v, slows down and stops in the house. From the point of view of a player at rest the initial kinetic energy is mv2/2 and the final kinetic energy is 0. Thus the player concludes that the amount of energy dissipated through the ice friction is mv2/2. At the same time from the point of view of a player which slides in the direction opposite to the stone motion with the constant velocity v the initial velocity of the stone is 2v and the final velocity of the stone is v so the initial kinetic energy is m(2v) 2/2 = 2mv2 and the final kinetic energy is mv2/2. Thus the sliding player can conclude that the amount of energy dissipated through ice friction is 3mv2/2. Which conclusion is correct? Explain the origin and the size of the difference.
Explanation / Answer
The first conclusion is correct because in the first case the observer is at rest and hence only the KE of the curling stone is in consideration.