A bus starting from rest moves with a uniform acceleration of 0.1, m s^{-2} for 2,min . Find (a) spe

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7. MOTION

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A bus starting from rest moves with a uniform acceleration of $0.1\, m s^{-2}$ for $2\,min$. Find $(a)$ the speed acquired, $(b)$ the distance travelled.

A

$v =6\, ms ^{-1}\;;\;d=360\,m$

B

$v =12\, ms ^{-1}\;;\;d=360\,m$

C

$v =24\, ms ^{-1}\;;\;d=720\,m$

D

$v =12\, ms ^{-1}\;;\;d=720\,m$

Solution

Initial speed of the bus, $u= 0$

Acceleration, $a =0.1\, m / s ^{2}$

Time taken, $t=2$ minutes $=120 \,s$

$(a)$ $v=u+a t$

$v =0+0 \times 1 \times 120$

$v =12\, ms ^{-1}$

$(b)$ According to the third equation of motion :

$v ^{2}- u ^{2}=2 \,as$

Where, $s$ is the distance covered by the bus

$(12)^{2}-(0)^{2}=2(0.1)\, s$

$s=720\,m$

Speed acquired by the bus is $12\, m / s$

Distance travelled by the bus is $720\, m$.

Standard 9

Science

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