Question

A particle of mass 0.2 kg is moving in One dimension under a force that delivers a constant power of 0.5 watt to the particle if the initial speed of the particle is zero the speed after 5 second is

Answer 1

P = 0.5 watt.

in 5 sec., W= Pt

⇒0.5×5

work ⇒ 2.5 joule

W = ΔKE           (work energy theorem)

2.5=1/2×0.2[v^2−0]

v = 5 ms^−1

Answer 2

Consider the power of the particle P = 0.5 watt.  

The watt is changed in five seconds. In 5 seconds, W = Pt, since 0.5 x 5.

Work is 2.5 joule.

According to the work energy theorem, W = KE. 2.5 = ½ x 0.2 (v2 -0).

Therefore, the speed of the particle after 5 second is 5 ms.