Question

two railway tracks are parallel to North South direction train A is moving with a speed of 40m/s from North to south along one track while train B is moving with a speed of 30m/s from south to North. calculate (1).relative velocity of B wrt A and (2.)relative velocity of ground wrt A​

Answer 1

Given :-

◉ Two railway tracks are parallel to North South ditection, Train A is moving with speed of 40 m/s from North to South along one track. Train B is moving with a speed of 30 m/s from South to north.

To Find :-

◉ Relative velocity of B w.r.t A

◉ Relative velocity of ground w.r.t A

Solution :-

Here, It is clear that the trains are moving towards each other.

• Velcoity of train A, v₁ = 40 m/s
• Velocity of train B, v₂ = - 30 m/s

One might ask why the velocity of train B is negative, It's because we assumed the direction of train A positive so the velocity of train B would be negative because It's moving in opposite direction.

So, Relative Velocity of B w.r.t A

⇒ Velocity of B + Velocity of A

⇒ v₂ - v₁

⇒ -30 - 40

⇒ -70 m/s

Hence, The relative speed of B w.r.t A is -70 m/s.

Here, The negative sign indicates the direction of train B, Any person in train A would see the train B moving towards them at a speed of 70 m/s.

Now, We have to find the relative velocity of ground w.r.t A, but the velocity of ground is 0 m/s and is fixed at a position.

So, Relative Velocity of ground w.r.t A

⇒ Velocity of ground - Velocity of A

⇒ 0 - v₁

⇒ - 40 m/s

Similarly, Here too, the negative sign indicates the direction of train A w.r.t ground. Train A would see the ground moving away at a speed of 40 m/s from it.

Answer 2

please adjust yourself to the attached picture.