A bullet of mass 0.010 kg and speed of 100 m/s is brought to rest in a wooden block after penetrating a distance of 0.10 m. The work done on the bullet by the block is
so my answer is 50 but I'm getting it wrong? I don't understand why??
work=KE 1/2(.010)(100)^2=50!
6 answers
well how do I figure how much work the wood block did on the bullet??
The work done is force times distance and that is 500 * 0.1 = 50 Joules which is what you had and I believe is correct either way you do it.
Ok so my professor FINALLY responded to me and said the answer is -50 J not 50J with no explanation.
What variable would I make negative to produce that answer? Would the velocity by negative since the wood is stopping the bullet?
What variable would I make negative to produce that answer? Would the velocity by negative since the wood is stopping the bullet?
Yes.
Went you slow something down your force is opposite to the velocity, you remove kinetic energy, negative work
Went you slow something down your force is opposite to the velocity, you remove kinetic energy, negative work
ok! finally some clarity. thank you!
V^2 = Vo^2 + 2a*d = 0,
V^2 = 100^2 + 2a*0.1 = 0,
a = -5*10^4 m/s^2.
F = M*a = 0.01 * (-5*10^4) = -500 N.
W = F*d = -500 * 0.1 = -50 J.
V^2 = 100^2 + 2a*0.1 = 0,
a = -5*10^4 m/s^2.
F = M*a = 0.01 * (-5*10^4) = -500 N.
W = F*d = -500 * 0.1 = -50 J.
5 answers