Given, mass of bead, m=400g=0.4kg Power delivered, P=1.2W Time, t=6s when the force is applied, it gives energy to the body. So from work energy theorem, W=
1
2
mv2−
1
2
mu2 =
1
2
mv2 Now, Power = Work ∕ Time P=W∕t ⇒P×t=W ⇒1.2×6=