A bus moving along a straight highway with speed of 72 mathrm{~km} / mathrm{h} is brought to halt wi

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2.Motion in Straight Line

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A bus moving along a straight highway with speed of $72 \mathrm{~km} / \mathrm{h}$ is brought to halt within $4 \mathrm{~s}$ after applying the brakes. The distance travelled by the bus during this time (Assume the retardation is uniform) is__________.$\mathrm{m}$.

A

$30$

B

$40$

C

$60$

D

$70$

(JEE MAIN-2024)

Solution

$\text { Initial velocity }=u=72 \mathrm{~km} / \mathrm{h}=20 \mathrm{~m} / \mathrm{s}$

$\mathrm{v}=\mathrm{u}+\mathrm{at}$

$\Rightarrow 0=20+\mathrm{a} \times 4$

$\mathrm{a}=-5 \mathrm{~m} / \mathrm{s}^2$

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

$\Rightarrow 0^2-20^2=2(-5) \mathrm{s}$

$\mathrm{s}=40 \mathrm{~m}$

Standard 11

Physics

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