Answer to Question #102921 in Classical Mechanics for Patrick Kariuki

Question

A 210 kg mass initially at rest on a smooth horizontal plane is acted upon by a force F parallel with the plane. If F is 1.4 tN where t is time in seconds, find for an interval of 30 seconds from rest: (a) the impulse (b) the velocity (c) the average force producing the same impulse.

Answer 1

Impulse is given by $\intop Fdt$

(a) Impulse= $\intop_0^{30}$ $1.4tdt$ $=1.4\times450=630Ns$

(b) Impulse= change in momentum $=\Delta p=m(v_f-v_i)$

$630=210(v-0) \newline v=3m/sec$

(c) $Impulse = avg. force \times time$

$630=F_{avg}\times30 \newline F_{avg}=21 N$