Question

A car starts from rest and accelerated uniformly to reach a speed of 21 m/s in 7.0 seconds. What was the speed of the object after 2 seconds

Answer 1

u=0, v=21, t=7

a= 21/7=3

v=21+3×2=27m/s

Answer 2

We know that,

Initial Velocity (u) = 0 ( Since the car starts from rest. )

Using (i) eqn of motion

v = u + at
21 = 0 + a(7) => a = 3 m/s²

Now, Again Using (i) eqn of motion

v = u + at => v = 0 + 3(2) = 6 m/s

Speed of car after 2 sec is 6 m/s


Hope it Helps!