Question

a boy starts moving with an acceleration of 4 metre per second square find out its speed after 4 seconds

Answer 1

u =0
a=4 m/s^2
t=4s
v=u+at
v=0+4m/s^2×4s
v=16m/s

Answer 2

a =( v - u)/t
u = 0m/s
t = 4sec
v = u+ at = 0 + 4*4 = 16 m/s