Find out the velocity of the mass:

A mass of weight 29.4 Newton is subjected into a time dependent force,

F(t)  = (3t 3  + 5) along x direction. Find out the velocity of the mass after

3 seconds, if initial velocity = 4 metres per second.

Solution

Letting the impulse momentum equation during a period from 0 to 3 seconds

where, mass m = W/g = 29.4 /9.8 = 3 kg.

and

V_{(t = 0)}  = 4 m / sec

                                 ∴ V₃  - 4 = 14

or, V₃ after 3 seconds = 18 metres/sec along x direction.