Distance - time graph of two trains are given below. trains start simultaneously in same direction.

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7. MOTION

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The distance$-$time graph of two trains are given below. The trains start simultaneously in the same direction.

$(i)$ How much ahead of $A$ is $B$ when the motion starts ?

$(ii)$ What is the speed of $B$ ?

$(iii)$ When and where $A$ will catch $B$ ?

$(iv)$ What is the difference between the speeds of $A$ and $B$ ?

$(v)$ Is the speed of either trains uniform or non uniform ? Justify your answer.

Option A

Option B

Option C

Option D

Solution

$(i)$ $100\, km$

$(ii)$ Speed of $B=\frac{O R}{P R}=\frac{150-100}{2-0}=\frac{50}{2}$

$=25 km h ^{-1}$

$(iii)$ They at a distance of $150\, km$ after $2$ hours.

$(iv)$ Speed of $A =\frac{150-0}{2-0}=\frac{150}{2}=75 km h ^{-1}$

Speed of $B=25 km h ^{-1}$

So the difference is $75-25=50 km h ^{-1}$

$(v)$ Uniform as the distance-time graph is a straight line.

Standard 9

Science

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