(A) Given,speed of the first car $v_1 = 18\,km/h$.Speed of the second car $v_2 = 27\,km/h$.Since the cars are moving towards each other,their relative

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(A) Given,speed of the first car $v_1 = 18\,km/h$.Speed of the second car $v_2 = 27\,km/h$.Since the cars are moving towards each other,their relative speed is $v_{rel} = v_1 + v_2 = 18 + 27 = 45\,km/h$.The initial distance between the cars is $d = 36\,km$.The time taken for the cars to meet is $t = \frac{d}{v_{rel}} = \frac{36}{45} = 0.8\,h$.The bird flies continuously at a constant speed $v_b = 36\,km/h$ until the cars meet.Therefore,the total distance covered by the bird is $D = v_b \times t = 36 \times 0.8 = 28.8\,km$.

Class 11 Physics 3-2.Motion in Plane Relative Velocity (river boat, rain, wind)

Difficult

$A$ bird is flying to and fro between two cars moving towards each other on a straight road. One car has a speed of $18\,km/h$ while the other has a speed of $27\,km/h$. The bird starts moving from the first car towards the other with a speed of $36\,km/h$. If the two cars were initially separated by $36\,km$,what is the total distance covered by the bird?

A
$28.8$
B
$36.4$
C
$58.2$
D
None of these

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3-2.Motion in Plane

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Relative Velocity (river boat, rain, wind)

$A$ river is flowing from west to east at a speed of $8\,m/min$. $A$ man on the south bank of the river,capable of swimming at $20\,m/min$ in still water,wants to swim across the river in the shortest time. He should swim in a direction

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When is the relative velocity of two moving cars greater than the individual velocity of both cars?

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Two parallel rail tracks run north-south. Train $A$ moves north with a speed of $54 \; km \; h^{-1},$ and train $B$ moves south with a speed of $90 \; km \; h^{-1}.$ What is the velocity of the ground in $m \; s^{-1}$ with respect to train $B$?

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Two trains $A$ and $B$ travel on two parallel rail tracks in opposite directions with speeds $v_1$ and $v_2$, respectively. They take $4 \ s$ to pass each other at these speeds. If the speed of train $A$ is increased by $50 \%$, then they take $3 \ s$ to pass each other. The ratio $v_1 / v_2$ is:

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$A$ man standing on a road holds his umbrella at $30^\circ$ with the vertical to keep the rain away. He throws the umbrella and starts running at $10 \ km/hr$. He finds that raindrops are hitting his head vertically. The speed of raindrops with respect to the road will be ......... $km/hr$.

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$A$ river is flowing from west to east at a speed of $8\,m/min$. $A$ man on the south bank of the river,capable of swimming at $20\,m/min$ in still water,wants to swim across the river in the shortest time. He should swim in a direction

When is the relative velocity of two moving cars greater than the individual velocity of both cars?

Two parallel rail tracks run north-south. Train $A$ moves north with a speed of $54 \; km \; h^{-1},$ and train $B$ moves south with a speed of $90 \; km \; h^{-1}.$ What is the velocity of the ground in $m \; s^{-1}$ with respect to train $B$?

Two trains $A$ and $B$ travel on two parallel rail tracks in opposite directions with speeds $v_1$ and $v_2$, respectively. They take $4 \ s$ to pass each other at these speeds. If the speed of train $A$ is increased by $50 \%$, then they take $3 \ s$ to pass each other. The ratio $v_1 / v_2$ is:

$A$ man standing on a road holds his umbrella at $30^\circ$ with the vertical to keep the rain away. He throws the umbrella and starts running at $10 \ km/hr$. He finds that raindrops are hitting his head vertically. The speed of raindrops with respect to the road will be ......... $km/hr$.

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