Question

A 2kg block at rest is acted upon by a constant force of 20N for 4 seconds. Find the final velocity of the block. Show complete solutions.

Answer 1

Given

Mass, m=2 kg

Force, F=20 N

Time, t=4 s

Find

The final velocity of the block v

Solution

By Newton's second law in terms of momentum change, we remember that

$$I=\Delta p=m\Delta v=m(v-v_i),\\\space\\ \Delta p=Ft,\\\space\\ m(v-v_i)=Ft,\\\space\\ 2(v-0)=20·4,\\\space\\ v=40\text{ m/s}.$$