Question

A 200 g whistle firecracker is set and fired horizontally in a straight line on top a smooth platform.

Its speed is 1.654 m/s in 0.35 seconds.

a) What is the momentum ?

b) The force in that time.

Answer 1

Given:

$v_i=0\:\rm m/s$

$v_f=1.654\:\rm m/s$

$m=0.2\:\rm kg$

$\Delta t=0.35\:\rm s$

(a)

$$p_i=mv_i=0.2*0=0\:\rm kg\cdot m/s$$

$$p_f=mv_f=0.2*1.654=0.33\:\rm kg\cdot m/s$$

(b)

$$F=\frac{\Delta p}{\Delta t}$$

$$F=\frac{0.33-0}{0.35}=0.945\:\rm N$$