Question

The velocity of an object increases at a constant rate from 20 m/s–1 to 50 m/ s–1 in 10s. find the acceleration.

Answer 1

As we know
a=v+u/t
a=20+50/10
a=70/10
a= 7m/s square

Answer 2

Initial velocity of object (u) = 20 m/s

Final velocity  of object (v)= 50 m/s

Time taken (t) = 10s  

Acceleration of the object is defined as rate of change of velocity.

or, a = (v - u) /t

or, a = ( 50 - 20) / 10

or, a = 30 / 10

or, a = 3 m/s²

Therefore, the acceleration of object is 3 m/s²