Same retarding force is applied to stop a train. train stops after 80, m . If speed is doubled, then

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2.Motion in Straight Line

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The same retarding force is applied to stop a train. The train stops after $80\, m$. If the speed is doubled, then the stopping distance will be

A

The same

B

Doubled

C

Halved

D

Four times

Solution

$\mathrm{v}^{2}=2 \mathrm{aS}$

$\mathrm{v}_{1}^{2}=2 \times \mathrm{a} \times 80, \mathrm{v}_{2}^{2}=4 \mathrm{v}_{1}^{2}$

$2 \mathrm{aS}=4 \times 2 \mathrm{a} \times 80 \Rightarrow \mathrm{S}=320$

Standard 11

Physics

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