A motor car moving with a uniform speed of 20,m/sec comes to stop on application of brakes after tra

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2.Motion in Straight Line

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A motor car moving with a uniform speed of $20\,m/\sec $ comes to stop on the application of brakes after travelling a distance of $10\,m$ Its acceleration is..........$m/{\sec ^2}$

A$20$

B$ - 20$

C$ - 40$

D$ + 2$

Solution

(b) From ${v^2} = {u^2} + 2aS$
$⇒$ $0 = {u^2} + 2aS$
$⇒$ $a = \frac{{ – {u^2}}}{{2S}} = \frac{{ – {{(20)}^2}}}{{2 \times 10}} = – 20m/{s^2}$

Standard 11

Physics

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