Question

One rocket is 500 m long and moving at a speed of 20 km/s. An asteroid is 2 km long and moving at a speed of 30 km/s. They are moving in opposite directions in straight lines. How long (in milliseconds) will it take them to cross each other? 1 millisecond is 0.001 second.

• A. 0.05
• B. 5
• C. 0.005
• D. 50

Answer 1

The correct option is D 50

Total length to be covered = 2.5 km

Relative speed = (30 + 20) km/s = 50 km/s

Time taken = 2.5/50 sec = 0.05 = 50 /1000 sec = 50 × 0.001 sec = 50 millisecond

Hence, option (D) is the correct answer.