Question

A rigid body of mass 6 kg is under a force which causes displacementin in it given by s= t2/4 metres where the is time the work done by the force in 2 second is

Answer 1

After 2s
S = t^2/4
S = 1m

v = dS/dt
v = 2t/4
v = t/2

a = dv/dt
a = 1/2 m/s^2

F = ma
F = 6*1/2
F = 3N

W = F * S
W = 3 * 1
W = 3J

Answer 2

"We can take m = 6 kg.  s= t2/4 metres. After 2s, we have to consider S = t^2/4 and get the value of S is 1 m.

V = dS/dt.  

v = t/2

a = dv/dt and hence we get 1/2 m/s^2

F = ma and hence we get F = 6*1/2

F = 3N

W = F * S

W = 3J

"