Physics

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A 60.0 kg girl stands up on a stationary floating raft and decides to go into shore. She dives off the 180 kg floating raft with a velocity of 4.0 m/s [W]. Ignore the substantial friction real objects in water experience.

a) What is the momentum of the girl as she is diving?
b) What is the momentum of raft as the girl is diving?
c) What is the final speed of the raft just after the girl dives?


a) * Let [W] be +ive.
p=mv
=(60.0kg)(4.0m/s)
=240 kg/(m/s)
Correct?

b) a little confused about this one, is it 0 because the raft doesn't have a velocity? or is it (180kg)(4.0m/s) because the raft will have a velocity equal and opposite to the girl?

c) for this one, i'm going to use p=p' (initial momentum=final momentum), and then work it out to be mv1 + mv2 = mv1' + mv2' where 1 is the girl, and two is the raft..
then work it out so both initial momentum's equal zero because they have no velocity (from rest), sub in the rest of the information and solve for v2'?

thanks in advance!

  • Physics -

    a right
    b> conservation of momentum says that the raft has equal and opposite momentum from the girl.
    c. set the momentums equal, and solve for raft velocity.

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