Starting from a stationary position, Rahul paddles his bicycle to attain a velocity of 8 m s–1 in 20 s. Then he applies brakes such that the velocity of the bicycle comes down to 4 m s-1 in the next 5 s. Calculate the acceleration of the bicycle in both the cases.
Answers
Starting from initial position, Rahul paddles his bicycle to attain a velocity of 8 m/s in 20 seconds.
As, the Rahul starts from rest mean his initial velocity is 0 m/s, his final velocity is 8 m/s and time taken by him is 20 seconds.
We have to find the acceleration of the bicycle.
Using the First Equation Of Motion:
v = u + at
Substitute the known values in the above formula,
→ 8 = 0 + a(20)
→ 8 = 20a
→ 0.4 = a
Therefore, the acceleration of the bicycle is 0.4 m/s².
In second part of the question it is given that, Rahul applied brakes such that the velocity of the bicycle comes down to 4 m/s in the next 5 sec.
Now, his final velocity in first case is equal to his initial velocity i.e. 8 m/s, final velocity is 4 m/s and time taken is 5 seconds.
Again we have to find the acceleration of the bicycle.
Using the First Equation Of Motion:
v = u + at
Substitute the values,
→ 4 = 8 + a(5)
→ 4 - 8 = 5a
→ -4 = 5a
→ -0.8 = a
(Negative sign shows retardation)
Therefore, the acceleration of the bicycle is 0.8 m/s².