A train travels east towards Hubli at 80 km/hr. A man on the train runs from the front of the train toward the rear of the train at 10 km/hr with respect to train. As he runs, he carries a plate of fruit with him. He notices a giant spider on the plate and throws the plate away from him (toward the rear of the train) at 20 km/hr with respect to him. Just after that instant, the startled spider jumps towards the man at 5 km/hr with respect to plate. The instant after the spider jumps toward the man, how fast is the spider approaching Hubli?
(A) 45km/hr
(B) 115 km/hr
(C) 55 km/hr
(D) 95 km/hr
Correct option (C) 55 km/hr
Explanation:
The relative velocity of man with the respect to train is 80 – 10 = 70 km/hr towards Hubli
The relative velocity of plate with respect to man is 70 – 20 = 50 km/hr towards Hubli
Therefore, velocity of spider approaching Hubli is 50 + 5 = 55 km/hr.