The relative velocity of B with respect to A is (a) – 90 km/h

Question

Two parallel rail tracks run north south. Train A moves north with a speed of 54 km/h and train B moves south with a speed of 90 km/ h

The relative velocity of B with respect to A is 

(a) – 90 km/h 

(b) –144 km/h 

(c) –132 km/h 

(d) none of these

Answer 1

Correct option (b) –144 km/h 

Explanation:

Let v_A = 54 km/h 

then v_B = – 90 km/h

∴ Relative velocity of B with respect to A

The velocity of train B with respect to train A appears 144 km/h along south.