Question

staring from rest the acceleration of a particle is a=2 (t-1).The velocity of the p article at t=5 second is?..answer is 15 m/s.

Answer 1

we know that, a= dv/dv
or, integration(a.dt) = v
hence, v = 2
$y= 2((x {}^{2} \div 2) - x)$
where, x = t
and, y = v

Therefore, v = 2(25/2 - 5) = 15

Remarks:- we use calculus method when motion is non-uniform otherwise equations of motion will be helpful.