**Question**

**A body of mass 100 g is at rest. A force acts on it for 3 seconds and the body attains a velocity of 15 cm/ s. Calculate the magnitude of force.**

**[Ans: 500 dyne]**

**Solution**

Mass (m) = 100 g

Initial velocity (u) = 0 cm/s

Final velocity (v) = 15 cm/s

Time (t) = 3 second

Force = m×(v - u)\over t

= 100 × (15 - 0)\over 3

= 100 × 5

= 500 dyne