Question

A shunting locomotive provides impulse of 40kN to set motion a stationary 8 tones wagon which then moves off freely at velocity u against a track resistance of 60N/tone and finally reaches a velocity v after 20 seconds. Find the values of u and v.

Answer 1

$p=40 kN\cdot s$

$p=m\cdot u \to$ $u=\frac{p}{m}=\frac{40000}{8000}=5m/s$

$F=ma\to a=F/m=(60\cdot 8)/8000=0.06m/s^2$

$v=u-at=5-0.06\cdot 20=3.8m/s$

Answer. $u=5$ $m/s$ ; $v=3.8$ $m/s$