A2L Item 105
- Description: What is the speed of a hoop rolling on an incline after its center has fallen a distance h?
- Goal: Problem solving
- Source: UMPERG-ctqpe147
- Keywords: Conservation, Energy, Mechanics, Rotational Motion
The question for students:
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 for teachers:
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.