A bus decreases its speed from $80\, km\, h^{-1}$ to $50 \,km h ^{-1}$ in $4\, s$. Find the acceleration of the bus.
A bus decreases its speed from $80\, km\, h^{-1}$ to $50 \,km h ^{-1}$ in $4\, s$. Find the acceleration of the bus.
Given $v=50 km h ^{-1}=50 \times \frac{5}{18}=\frac{125}{9} m s ^{-1}$
$u=80 km h ^{-1}=80 \times \frac{5}{18}=\frac{200}{9} m s ^{-1}$
$t=4 s$
Using the expression $v=u+a t,$ we have
$a=\frac{v-u}{t}=\frac{125-200}{9 \times 4}=-2.083 m s ^{-2}$
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