Question

A car is moving along a straight highway with a speed of 90kmph brought to stop within a distance of 200m.What is the acceleration of the car which is assumed to be uniform? how long does it take for the car to stop?​

Answer 1

Answer:

Given,

Velocity of car v=126 km/h=35 m/s

Displacement s=200 m

Final velocity v=0 m/s

Apply second kinematic equation to calculate retardation a

v

2

−u

2

=2as

⇒a=

2s

v

2

−u

2

=

2×200

0−35

2

=−3.0625 m/s

2

Apply first kinematic equation to calculate time t

v=u+at

⇒t=

a

v−u

=

3.0625

0−35

=11.43 sec

Hence, retardation is 3.06 m/s

2

and time take to stop is 11.4 sec