(B) The initial distance between the two trains is $d = 120\, km$. Each train moves with a velocity $v_t = 60\, km/hr$ towards each other. The relativ

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(B) The initial distance between the two trains is $d = 120\, km$. Each train moves with a velocity $v_t = 60\, km/hr$ towards each other. The relative velocity of the trains is $v_{rel} = 60 + 60 = 120\, km/hr$. The time taken for the trains to crash is $t = d / v_{rel} = 120\, km / 120\, km/hr = 1\, hr$. Since the sound waves travel continuously at a constant speed $v_s = 1200\, km/hr$ in the air until the moment of the crash,the total distance $D$ covered by the sound waves is given by $D = v_s \times t$. Substituting the values,$D = 1200\, km/hr \times 1\, hr = 1200\, km$.

Class 11 Physics Motion in Straight Line Relative Motion in One Dimension

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Two trains $A$ and $B$,initially $120\, km$ apart,start moving towards each other on the same track with a velocity of $60\, km/hr$ each. At the moment of start,train $A$ blows a whistle,which reflects off train $B$ and subsequently reflects off train $A$,and so on. If the velocity of sound waves in air is $1200\, km/hr$,what is the total distance travelled by the sound waves before the trains crash (in $km$)?

A
$2400$
B
$1200$
C
$240$
D
$120$

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Motion in Straight Line

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Relative Motion in One Dimension

Two bodies start moving from the same point along a straight line with velocities $v_1 = 6 \, m/s$ and $v_2 = 10 \, m/s$,simultaneously. After what time will their separation become $40 \, m$?

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$A$ car is standing $200\, m$ behind a bus,which is also at rest. The two start moving at the same instant but with different forward accelerations. The bus has an acceleration of $2\, m/s^2$ and the car has an acceleration of $4\, m/s^2$. The car will catch up with the bus after a time of:

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Explain the concept of relative velocity and its two cases.

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$A$ bus starts moving with an acceleration of $2\,m/s^2$. $A$ cyclist,$96\,m$ behind the bus,starts moving simultaneously towards the bus at a constant speed of $20\,m/s$. After how many seconds will the cyclist be able to overtake the bus?

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Two cars $A$ and $B$ are moving in the same direction with velocities $30 \, m/s$ and $20 \, m/s$. When car $A$ is at a distance $d$ behind car $B$,the driver of car $A$ applies brakes,producing a uniform retardation of $2 \, m/s^2$. There will be no collision when ......... $m$.

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Two bodies start moving from the same point along a straight line with velocities $v_1 = 6 \, m/s$ and $v_2 = 10 \, m/s$,simultaneously. After what time will their separation become $40 \, m$?

$A$ car is standing $200\, m$ behind a bus,which is also at rest. The two start moving at the same instant but with different forward accelerations. The bus has an acceleration of $2\, m/s^2$ and the car has an acceleration of $4\, m/s^2$. The car will catch up with the bus after a time of:

Explain the concept of relative velocity and its two cases.

$A$ bus starts moving with an acceleration of $2\,m/s^2$. $A$ cyclist,$96\,m$ behind the bus,starts moving simultaneously towards the bus at a constant speed of $20\,m/s$. After how many seconds will the cyclist be able to overtake the bus?

Two cars $A$ and $B$ are moving in the same direction with velocities $30 \, m/s$ and $20 \, m/s$. When car $A$ is at a distance $d$ behind car $B$,the driver of car $A$ applies brakes,producing a uniform retardation of $2 \, m/s^2$. There will be no collision when ......... $m$.

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