A ship A is moving Westwards with a speed of 10 km h^(-1)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 :

A ship A is moving Westwards with a speed of 10 km h^(-1)and a ship B

1.	A ship A is moving Westwards with a speed of 10 km h^(-1)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 :
Answer» 0 hr 5 hr `5sqrt2 hr ` `10 sqrt2 hr` SOLUTION : `\|vecV _(AB)\| = sqrt ( 10 ^(2) + 10 ^(2)) = 10 sqrt2 kmph` distance `OB = 100 COS 45 ^(@) = 50 sqrt2km` Time TAKEN to reach the shortest distance between `A&B = (50 sqrt2)/( \|vecV _(BA)\|) = (50 sqrt2)/(10 sqrt2)` `t _(SN) = 5 HRS.`