Question

6. A lumberjack is standing on a log floating on a lake. She starts from rest, then runs along the log to the end, when she jumps from the first log onto a second. After landing safely on the second log, she slows down and ends up standing on the second log. Both logs both have masses of 150 kg each and the mass of the lumberjack is 70 kg. The lumberjack reaches a speed of 7.0 m/s relative to the shore during her jump. What are the speeds of the two logs and of the lumberjack after she has stopped on the second log

Answer 1

Answer:

a) -3.267 m/s

b) 2.227 m/s

Explanation:

As per the conservation of momentum

m1v1 + m2v2=0

m1= mass of log

m2 = mass of lumber jack

v1 = velocity of log

v2 = velocity of lumber jack

a) Velocity of first log

$-\frac{70*7}{150} = -3.267$ m/s

b) m1v1 + m2v2 = m3v3

Velocity of log

= $\frac{70*7}{150+70} \\2.227$