A train is travelling at a speed of 90, km h ^{-1} . Breaks are applied so as to produce a uniform a

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7. MOTION

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A train is travelling at a speed of $90\, km h ^{-1}$. Breaks are applied so as to produce a uniform acceleration of $0.5\, m s ^{-2}$. Find how far the train will go before it is brought to rest.

Option A

Option B

Option C

Option D

Solution

Given $u=90 km h ^{-1}=5 \times \frac{90}{18}=25 m s ^{-1}, v=0$

$a=-0.5 m s ^{-1}, S =?$

Using

$v^{2}-u^{2}=2 a S$

$0-(25)^{2}=2 \times-0.5 \times 5$

or $S =625 m$

Standard 9

Science

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