Question

a velocity of A lumberjack (mass-98 kg) is standing at rest on one end of a floating log (mass230 kg) that is also at rest. The lumherjack runs to the other end of the log, attaining an identical laating log that is initially at rest. Neglect any Triction and resistance between the logs and the water. 2.8 mfs relative to the shore, and then haps onto ting log that is (a) what is the velocity of the rirst log just before the lumberjack jumps or? (indicate the direction of the velocity by the sign or your answers. m's (b) Dete㎜ inc to vclocity of the second log if the lumberjack comes to rest on it. mys

Could you please explain your answer? Thank you

Answer 1

let's say that lumberjack will be m and v. log will be M and V.

a) conservation of momentum
mv(i) + MV(i) = mv(f) +MV(f) since the beginnig velocity of both of them is zero so
0 = 98(2.8) + 230V(f)
V(f) = -1.193 m/s

b) again concervation of momentum
mv(i) + MV(i) = (m + M)v(f)
98(2.8) + 230(0) = (98+230)v(f)
v(f) = +0.837 m/s