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

Answer:

Acceleration a=

t

v−u

=

10s

50 ms

−1

−20 ms

−1

or a=

10s

30 ms

−1

=3 ms

−2

Answer 2

Answer:

a=2m/s

v=70ms

Explanation:

For uniform acceleration, equations of motion are valid

v=u+at

50=30+10a

20=10a

a=2ms^2

velocity after 20s

v=u+at

v= 50 + 20 (initial velocity is taken as velocity after 10s so time left = 20 - 10 = 10s)

v = 50 +20

v = 70ms