A boat is moving with a velocity vw= 5 km/hr relative to water. At time , the boat passes through a piece of cork floating in water while moving downstream. If it turns back at time `t_(1)=30` min,
(a) when the boat meet the cork again?
(b) The distance travelled by the boat during this time.

Explanation

Consider an observer attached with cork. The boat has same speed upstream and downstream relative to cork. Hence., if the boat travels for 30min. while moving away from cork, it travel the same time while approching the cork.
Therefore the boat meet thecork at
T=2t = 60 min = 1h
The distance travelled by boat in this time,
`S=V_(BW) xx T = 5 xx 1= 5`km