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7. MOTION
medium
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 $720\, m$.
Std 9
Science
