Question

Define relative velocity. with an example

Answer 1

The relative velocity of an object A with respect to another object B is the velocity that object A would appear to have to an observer situated on object B moving along with it.

example- you are in a bus and it goes with the velocity of 50 m/s to the east, then a truck passes you with a velocity of 60m/s to the east.

Answer 2

The rate of change of the relative position of an object with respect to the other  object is known as the relative velocity of that object with respect to the other.

Example:

A train A is moving on a straight track (or railway line) from North to South with a speed of 60$\frac{km}{h}$. Another train B is moving from South  to North with a speed of 70$\frac{km}{h}$. What is the velocity of B relative to the train  A?

soln:

Considering the direction from South to North as positive, we have  velocity (vB) of train B = + 70$\frac{km}{h}$

and, velocity (vA) of train A = – 60$\frac{km}{h}$

Hence, the velocity of train B relative to train A

= $v_{B}- v_{A}$

= 70 – (– 60) = 130$\frac{km}{h}$

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