Starting from a stationary position, Rahul paddles his bicycle to attain a velocity of 6 m s–1 in 30 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.

NCERT Class IX
Sciences - Main Course Book

Chapter 8. Motion

1

Answers

2015-05-21T23:31:08+05:30
CASE I

Given,
Initial Velocity(u)=0m/s
Final Velocity(v)=6m/s
time(t)=30 secs
Acceleration=?

v=u +at
v=0+a(30)
6=0+a(30)
6-0=a(30)
6/30=a
a=1/5 m/s-2
a=0.2m/s-2

CASE II

Given,

Initial Velocity(u)=6m/s
Final Velocity(v)=4m/s
time(t)=5 secs
acceleration=?

v=u+at
4=6+a(5)
4-6=a(5)
-2/5=a
a=-0.4m/s-2


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