Question

Ramu and Somu are running towards north with $3{\text{ }}m/s$ and $4{\text{ }}m/s$ . Their friend Srinu is running towards south with $2{\text{ }}m/s$ . Then the magnitude of relative velocity of Ramu w.r.t Srinu.
A. $1m/s$
B. $5m/s$
C. $4m/s$
D. $6m/s$

Answer 1

To discover the relative velocity of Ramu with respect to Srinu, we will first discuss relative velocity, and then solve the above question by simply subtracting the relative velocity of Ramu and Srinu, as they are going in different directions.

Complete step by step answer:
Before we get into the question, let's talk about the word relative velocity, to which the question is related. This is the rate at which one object moves in relation to another object, which could be stationary, moving slowly, moving at the same pace, travelling faster, or moving in the opposite direction.

First of all let us write the velocity of each Ramu, somu and srinu. Velocity of Ramu running towards the north is $3{\text{ }}m/s$. Velocity of Somu running towards north is $4{\text{ }}m/s$. And, velocity of srinu who is running in the opposite direction of ramu and somu in the north direction is $2{\text{ }}m/s$ . Now, we are asked to find the relative velocity of Ramu with respect to Srinu and both of them are running in the opposite direction.So, relative velocity of Ramu w.r.t. Srinu is ;
Velocity of Ramu - Velocity of Srinu
$3m/s - 2m/s \\\ \therefore 1m/s$
Thus, the magnitude of relative velocity of Ramu with respect to srinu is $1m/s$

So, the correct option is A.

Note: The sign merely denotes the direction, not the magnitude. When addressing numerical problems involving relative velocities, keep in mind that if the two bodies are travelling in the same direction, the relative velocities are additive. The relative velocities will be subtractive if the bodies travel in different directions.