Question

Question 30:
A cyclist is travelling at 15 m s-1. She applies brakes so that she does not collide with a wall 18 m away. What deceleration must she have ?

Lakhmir Singh Physics Class 9

Answer 1

Since object is decelerating, acceleration comes in negative.

V is 0 m/s because in order to not get hit with the wall, final velocity must be O in order to fully stop the motion of the body.

Answer 2

Dear Student,

◆ Answer -

a = -6.25 m/s²

● Explaination -

# Given -

u = 15 m/s

s = 18 m

# Solution -

For cyclist to stop before wall, v = 0.

Applying Newton's 3rd law of kinematics -

v² = u² + 2as

0² = 15² + 2 × a × 18

a = -225/36

a = -6.25 m/s²

Therefore, cyclist must have deceleration of 6.25 m/s².

Thanks dear...