Question

a scooter moving with a velocity of 18km/h is brought to rest in 5 sec by applying brakes. What is the retardation produced

Answer 1

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Answer 2

Concept:

• One-dimensional motion
• Kinematics equations
• Retardation
• conversion of physical quantities

Given:

• Initial velocity of the scooter u = 18 km/h = 18 *1000/3600 = 18* 5/18 = 5 m/s
• The scooter comes to a rest
• So the final velocity of the scooter v = 0 m/s
• Time taken for the scooter to come to a rest = 5 s

Find:

• The retardation of the scooter

Solution:

We know the kinematics equation

v = u +at

v = 0, u = 5 m/s, t = 5s

0 = 5 + a(5)

0 = 5 + 5a

5a = 0-5

5a = -5

a = -5/5

a = -1 m/s

The acceleration is -1m/s.

The question has asked for retardation which is just the negative value of acceleration.

Retardation = -(-1) m/s = 1 m/s.

The retardation produced is 1 m/s.

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