Question

The velocity of an object increases at a constant rate from 30 ms-1 to 50 ms-1 in 10 s. Find the acceleration of the object. Hence find the velocity after 20 s if the object moves with uniform acceleration.

Answer 1

For uniform acceleration, equations of motion are valid

v = u+at

50 = 30+10a

20 = 10a

a = 2m/s²

Velocity after 20 seconds

v = u+at

v = 50+2×10 (Initial velocity is taken as velocity after 10 seconds so time left = 20-10 = 10 seconds)

v = 50+20

v = 70m/s

Answer 2

For uniform acceleration, equations of motion are valid

v = utat

50 = 30+10a

20 = 10a

a = 2m/s²

Velocity after 20 seconds.

v = utat

v = 50+2×10 (Initial velocity is taken as velocity after 10 seconds so time left = 20-10 10 seconds)

v = 50+20

v = 70m/s