A 1.2 kg rock is thrown through a glass window. It hits the window with a speed
ID: 1410498 • Letter: A
Question
A 1.2 kg rock is thrown through a glass window. It hits the window with a speed of +5.0 m/s, and after the window shatters, it has a speed of +3.0 m/s. If the glass breaks in 0.002 s, what force did the glass exert on the rock?
A : +1200 N
B : -1200 N
C : -4800 N
D : +4800 N
E : None of the choices are correct.
Q2 - If a 23.0 g bullet is stopped in a wooden block of mass 8.0 kg, and the speed of the bullet–block system immediately after the collision is 0.40 m/s. what is the initial speed of the bullet before penetrating the block?
A : 155 m/s
B : 175 m/s
C : 125 m/s
D : 140 m/s
E : 225 m/s
Explanation / Answer
Q1)
Force = change in momentum / time
F = 1.2 (3-5) /0.002
F = -1200 N B
Q2)
conserving momentum
0.023 x V = 8.023 x 0.4
V = 140 m/sec ( D)
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