9. A 30-gram bullet initially travelling at 500 m/s penetrates 12 cm into a wood
ID: 1309946 • Letter: 9
Question
9. A 30-gram bullet initially travelling at 500 m/s penetrates 12 cm into a wooden block. What average force does the bullet exert on the block? Choose the closest answer from the provided below.
a. 3.125 x 10^4 N
b. 0.525 x 10^3 N
c. 125 x 10^2 N
d. 2220 N
(please explain the answer)
10.) A 1 kg block is attached to a spring with force constant 200 N/m is free to move on a frictionless surface. The block is released from rest when the spring is stretched to 0.2 m. At the instant block is released, find the force on the block and it's direction, and the potential energy (PE). Choose from closest answer below.
a. F = -40N x, PE = 4 Joules
b. F = 2N x, PE = 40 Joules
c. F = -0.5 N y, PE = 4 Joules
d. F = 40 N x, PE = 40 Joules
(please explain the answer)
Explanation / Answer
W = change in KE
F*S*cos180 = 0 - 0.5*v^2
F*0.12 = 0.5*0.03*500^2
F = 31250 N
a. 3.125 x 10^4 N
10)
F = -kx = -200*0.2 = -40N
PE = (1/2)*k*x^2 = (1/2)*200*0.2^2 = 4 joules
a. F = -40N x, PE = 4 Joules
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