Answer: i got 0.4s
Step-by-step explanation:
As the object is moving under constant force,we can apply the equation,
v=u+at where, v is the velocity attained after time t which had an initial velocity of u.
a=F/m=50/4=12.5ms^-2
Given, u=0
So, if v=5 then, t = 512.5 = 0.4s