A boat takes 2 hours to travel 8km and back in still water lake.With water velocity of 4 kmph the time taken for going upstream of 8km and coming back is.

Question

A boat takes 2 hours to travel 8km and back in still water lake.With water velocity of 4 kmph the time taken for going upstream of 8km and coming back is. (A) 160 minutes (B) 80 minutes (C) 320 minutes (D) 180 minutes

Tardigrade Admin · Accepted Answer

VB = (8 + 8/2) = 8 kmph t = t1 + t2 = (8/νB + νr) + (8/νb - νr) = 160 min

Q. A boat takes 2 hours to travel 8km and back in still water lake.With water velocity of 4 kmph the time taken for going upstream of 8km and coming back is.

160 minutes

80 minutes

320 minutes

180 minutes

$V_{B} = \frac{8 + 8}{2} = 8 km p h$
$t = t_{1} + t_{2} = \frac{8}{ν _{B} + ν _{r}} + \frac{8}{ν _{b} - ν _{r}} = 160 min$

Q. A boat takes 2 hours to travel 8km and back in still water lake.With water velocity of 4 kmph the time taken for going upstream of 8km and coming back is.

160 minutes

80 minutes

320 minutes

180 minutes

VB​=28+8​=8kmph t=t1​+t2​=νB​+νr​8​+νb​−νr​8​=160min

$V_{B} = \frac{8 + 8}{2} = 8 km p h$
$t = t_{1} + t_{2} = \frac{8}{ν _{B} + ν _{r}} + \frac{8}{ν _{b} - ν _{r}} = 160 min$