Which one of the following represents the time-displacement graph of two objects

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easy

Correct option is

When velocity of  A= velocity of B, then, relative velocity is zero

Displacement –time graphs of A and B must have same slope (other than zero).

Q1

Two particle start moving from the same point along the same straight. The first moves with constant velocity v and the second with constant acceleration a. During the time that elapses before the second catches the first, the greatest distance between the particle is

Q2

The velocity –time graphs of two particles P1 and P2 are shown in the adjoining figure. Their relative velocity at time t is

Q3

The width of a river is 1km. The velocity of a boat is 5 km/h. The boat covered the width of river in shortest time 15 minute. Then the velocity of river stream is

Q4

A ship A is Westwards with a speed of 10 km h-1 and a ship B 100 km South of A, is moving Northwards with a speed of 10 kmh-1. The time after which the distance between them becomes shortest, is

Q5

A ball A is dropped from a building of height 45 m. Simultaneously another identical ball B is thrown up with a speed 50 m s-1. The relative speed of ball B. w.r.t. ball A at any instant of time is (Take g = 10ms-2)

Q6

A ball A is thrown vertically upwards with speed u. At the same instant another ball B is released from rest at height h. At time t, the speed of a relative to B is

Q7

Two town A and B are connected by a regular bus service with a bus leaving in either direction every T minutes. A man cycling with a speed of 20 km h-1 in the direction A to B notices that a bus goes past him every 18 min in the direction of his motion, and every 6 min in the opposite direction. The period T of the bus services is

Q8

Two parallel rail tracks run north –south. On one track train A moves north with a speed of 54 km h-1 and on the other track B moves south with a speed of 90 km h-1. The velocity of train A with respect to train B is .

Q9

A train A which is 120 m long is running with velocity 20 m/s while train B which is 130 m long is running  in opposite direction with velocity 30 m/s What is the taken by train B to cross the train A ?

Q10

At a metro station, a girl walk up a stationary escalator in time t1. If she remains stationary on the escalator take her up in time t2. The time taken by her to walk up on the moving escalator will be.

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Text Solution

<img src="https://d10lpgp6xz60nq.cloudfront.net/physics_images/NCERT_OBJ_FING_PHY_XI_C03_E01_100_O01.png" width="30%"><img src="https://d10lpgp6xz60nq.cloudfront.net/physics_images/NCERT_OBJ_FING_PHY_XI_C03_E01_100_O02.png" width="30%"><img src="https://d10lpgp6xz60nq.cloudfront.net/physics_images/NCERT_OBJ_FING_PHY_XI_C03_E01_100_O03.png" width="30%"><img src="https://d10lpgp6xz60nq.cloudfront.net/physics_images/NCERT_OBJ_FING_PHY_XI_C03_E01_100_O04.png" width="30%">

Answer : B

Solution : When velocity of A = velocity of B, then relaitve velocity is zero. <br> `therefore` Displacement-time graphs of A and B must have same slope (other than zero).