A bus decreases its speed from 80, km, h ^{-1} to 60 ,km, h ^{-1} in 5, s . acceleration(in m / s ^{

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7. MOTION

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A bus decreases its speed from $80\, km\, h ^{-1}$ to $60 \,km\, h ^{-1}$ in $5\, s$. Find the acceleration(in $m / s ^{2}$) of the bus.

A

$4.44$

B

$-1.112$

C

$-2.112$

D

$7.77$

Solution

Initial speed of the bus, $=80 \times \frac{5}{18}=22.22 \,m / s$

Final speed of the bus, $=60 \times \frac{5}{18}=16.66\, m / s$

Time take to decrease the speed, $t=5 \,s$

Acceleration, $a =\frac{v-u}{t}=\frac{16.66-22.22}{5}=-1.112\, m / s ^{2}$

Standard 9

Science

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