Question

${\mathfrak{\blue{\clubs{\large{\underline{Question}}}}}}$
Find the initial velocity of a car which is stopped in 10s by applying the brakes. The retardation due to brakes is 2.5 m/s sqr.

Define retardation please.


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Answer 1

Required Answer :

Given :

• Final Velocity ( v ) = 0
• Time ( t ) = 10s
• Acceleration ( a ) = -2.5m/s² ( It is negative because it is retarding )

To Find :

• Initial velocity ( u ) = ?

Formula :

${\sf{:\implies \bold{ v = u+ at} }}$

let's solve !

${\sf{:\implies v = u+ at }}$

${\sf{:\implies 0 = u+ (-2.5) \times 10}}$

${\sf{:\implies 0 = u -25}}$

${\sf{:\implies u = -25-0}}$

${\sf{:\implies u = \green{\bold{ 25m/s}}}}$

Define retardation -

• If the final velocity of the body is not greater than initial velocity then in this case acceleration will be negative.

• It is called negative acceleration or we can also say retardation .

• For Example - A ball thrown vertically upward has -ve acceleration .

Answer 2

it is very easy :) !

Find the initial velocity of a car which is stopped in 10s by applying the brakes. The retardation due to brakes is 2.5 m/s sqr.

→ 25 m/s

Define retardation please.

→ negetive acceleration