A force applied on a body of mass 4 kg for 5 s

CBSE Class 9 CBSE Class 9 Science
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1

A force applied on a body of mass 4 kg for 5 s changes its velocity from 10 m to 20 m. Find the power required.

2

Given, m = 4 kg, t = 5 s, u = 10 m, v = 20 m,
p = ?
Power = W/t = Change in KE / Time taken = 1/2 x m( ${{v}^{2}}$ - ${{u}^{2}}$)/t
= 1/2 x (20 x 20 - 10 x 10) / 5 = 1/2 x 300 / 5 =120 J