Question

A ship A is moving Westwards with a speed of
10 km/hr and a ship B 100 km South of A is moving Northwards with a speed of 10 km h-1. The time after which the distance between them becomes shortest, is

(1) 10 root 2 hour (2) 0 hour
(3) 5h
(4)5 root 2 hour​

Answer 1

If a moves north in 100km in so 10 hrs

Now a will also move the same 100 km

Beacuse of them both is Same

But if we take 50km only then A will take same

Both will form right angle result displacement is 50root2 and it is short

Now so it is found 50km is shortest.

Time taken to establish it is 50÷10

So answer is 5 hours