The next two questions refer to the following physicalsituation:
Two blocks (masses m1 = 30 kg andm2 = 7 kg) sit atop one another as shown below.The coefficient of static friction between the blocks isμs= 0.32.  There is no frictionbetween the lower block and the surface on which it rests. Aconstant external force F is applied to the lowerblock.
What is Fmax, the maximum magnitude of thisforce such that the upper block does not slide with respect to thelower block?
| a. | Fmax = 158 N |
| b. | Fmax = 116 N |
| c. | Fmax = 61 N |
| d. | Fmax = 80 N |
| e. | Fmax = 141 N |
If there is kinetic friction between the lower block and thesurface, the magnitude of the maximum possible forceFmax that can be exerted on the lower blockbefore the upper block starts sliding with respect to the lowerblock...
| a. | stays the same. |
| b. | decreases. |
| c. | increases. |
A precocious child wants to determine the moment of inertia,Io, of the local merry-go-round. The childmeasures the radius of the merry-go-round (R = 2 m), thenweighs herself (m = 25 kg), then notices that when shemoves from the center of the merry-go-round to the rim, therotational velocity of the merry-go-round changes from 0.3 rev/secto 0.2 rev/sec. If the child treats herself as a point mass, whatmoment of inertia does she estimate for the merry-go-round?
| a. | Io = 500 kg-m2 |
| b. | Io = 300 kg-m2 |
| c. | Io = 200 kg-m2 |
| d. | Io = 400 kg-m2 |
| e. | Io = 100 kg-m2 |
As the child moves from the center of the merry-go-round to therim, the kinetic energy of the child plus the merry-go-round...
| a. | decreases. |
| b. | stays the same. |
| c. | increases |
