A bus decreases its speed from 80, km, h^{-1} to 50 ,km h ^{-1} in 4, s . acceleration of bus.

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7. MOTION

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A bus decreases its speed from $80\, km\, h^{-1}$ to $50 \,km h ^{-1}$ in $4\, s$. Find the acceleration of the bus.

Option A

Option B

Option C

Option D

Solution

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

$a=\frac{v-u}{t}=\frac{125-200}{9 \times 4}=-2.083 m s ^{-2}$

Standard 9

Science

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