Question

A particle of mass 4 kg at rest is acted upon by a force 20 n for 4 s. its kinetic energy after 4 seconds is

Answer 1

Mass = 4kg

Force= 20N

Time = 4s

K.E.=?

W.k.t.

K.E.= 1/2mv²

Therefore

F=ma

20=4(a)

a=5ms^-2

so,a=v/t

v=a.t

v=20ms^-1

So,K.E=1/2(4)(20)²

=800 Joule.