Goal: Problem solving
Source: UMPERG-ctqpe147
A hoop of mass 4 kg and radius r rolls
without slipping down an incline 30° to the horizontal. The hoop is
released from rest. What is the speed of the hoop after its center has
fallen a distance h?
- (4g(h-r))1/2
- (2gh)1/2
- (gh)1/2
- (0.5g(h+r))1/2
- none of the above
- cannot be determined
Commentary:
Answer
(3.) Students should realize that the speed cannot depend upon the
radius. Answer #2 is the speed that a falling point mass would have and
the hoop must have less than that.