In: Physics
The next two questions refer to the following physical situation:
Two blocks (masses m1 = 30 kg and m2 = 7 kg) sit atop one another as shown below. The coefficient of static friction between the blocks is μs= 0.32. There is no friction between the lower block and the surface on which it rests. A constant external force F is applied to the lower block.
What is Fmax, the maximum magnitude of this force such that the upper block does not slide with respect to the lower block?
a. |
Fmax = 158 N |
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b. |
Fmax = 116 N |
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c. |
Fmax = 61 N |
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d. |
Fmax = 80 N |
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e. |
Fmax = 141 N |
If there is kinetic friction between the lower block and the surface, the magnitude of the maximum possible force Fmax that can be exerted on the lower block before the upper block starts sliding with respect to the lower block...
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 child measures the radius of the merry-go-round (R = 2 m), then weighs herself (m = 25 kg), then notices that when she moves from the center of the merry-go-round to the rim, the rotational velocity of the merry-go-round changes from 0.3 rev/sec to 0.2 rev/sec. If the child treats herself as a point mass, what moment of inertia does she estimate for the merry-go-round?
a. |
Io = 500 kg-m2 |
|
b. |
Io = 300 kg-m2 |
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c. |
Io = 200 kg-m2 |
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d. |
Io = 400 kg-m2 |
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e. |
Io = 100 kg-m2 |
As the child moves from the center of the merry-go-round to the rim, the kinetic energy of the child plus the merry-go-round...
a. |
decreases. |
|
b. |
stays the same. |
|
c. |
increases |