Question

Suppose you are standing on a frozen pond while carrying three wooden blocks that weigh 3.0 kg each. You need to horizontally throw each block away from you at a rate of 5.0 m/s to be able to get to the shore of the pond. Assuming that your mass is 65.0 kg, how fast are you moving after you throw the first block?

Answer 1

Solution,

Given

Mass of person = 65 kg

Mass of blocks = 3 kg

Rate at which block throw 5 m/sec

Using momentum conservation

P_Initial = P _Final

let V_p is velocity of person after throwing block.

Initially momentum is Zero

P _Initial= 0

Momentum final = momentum of blocks + momentum of person

$= 3 * 5 + 71 * V_p$

V _P = - 0.211m/sec

Velocity is negative hence minus sign shows that person move back side with velocity 0.211 m/ sec