Question

18. A body starting from rest acquires a velocity of 18 cm/s in 3 s. If the body has a mass of 15 g. What force is exerted on the body?

Answer 1

The acceleration and force (by Newton's second law):

$$a=\frac vt,\\\space\\ F=ma=m\frac vt=0.015·\frac{0.18}{3}=9·10^{-4}\text{ N}.$$