Daily survey results - Problem 3/260

The rebound angle theta is 60 degrees, regardless of the COR, e (0):  

As we know (and as presented in the solution video), the "n" component of the rebound velocity of the sphere is decreased as e is decreased; the "t" component is unchanged. Therefore, the angle theta formed by the rebound velocity vector decreases as e is decreased. For example, when e = 1, theta = 60°; when e = 0, theta = 0.

As e is decreased, the rebound speed decreases (3):

As described above, the "n" component of rebound velocity is decreased as e is decreased. The "t" component is unchanged as e is decreased. Therefore, the rebound speed (magnitude of velocity) decreases as e is decreased.

As e is decreased, the "t" component of rebound velocity is unchanged (4):

As discussed above, this statement is true.

If e = 0, then v = 0 (1):

If e = 0, the "n" component of rebound velocity is zero. However, the "t" component is unchanged and is therefore not zero. Therefore, the rebound speed is NOT zero.

As e is decreased, the "impulse" of the impact force decreases (2):

As e is decreased, the "n"component of rebound velocity is decreased. Since the impulse, I, of the impact force is given by:

         I = m*v_n2 - m*v_n1

a decrease in v_n2 will decrease the value of I.

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