Question
The position x of a particle moving along x-axis at time t is given by the equation t = √x + 2 , where x is in metres and t in seconds. Find the work done by the force in first four seconds.
Joshi sir comment
t = √x + 2
implies x = (t-2)2
so dx/dt = v = 2(t-2)
and dv/dt = a = 2
so F = ma = 2m
and x(initial) = 4 m
x (final) = 4 m
so displacement = 0 m
so work = 0 J