Question

If a man rows at 6 km/h in still water and 4.5 km/h against the current, then his along the current is?

Answer 1

$V_m : \texttt{\green{velocity \: of \: man}}$

$V_w : \texttt{\green{velocity \: of \: water}}$

$V_{mw} : \texttt{\green{velocity \: of \: man\: w.r.t \: boat}}$

Given:-

• $V_m = 6 \: kmph$
• $V_{mw}(upstrem) = 4.5 \: kmph$

To Find:-

Velocity of man w.r.t Water( $V_{mw}$ )downstream

Explanation:-

W.k.t,

When , the boat travels upstream

$\boxed{\bold{V_{mw = }V_m - V_w}}$

On putting values

${\rightarrow} 4.5 = 6 - V_w$

${\rightarrow} V_w = 6-4.5$

${\rightarrow}V_w = 1.5 \: kmph$

When , the boat travels down stream

$\boxed{\bold{V_{mw = }V_m +V_w}}$

On putting values ,

${\rightarrow} V_{mw} = 6 + 1.5$

${\rightarrow} V_{mw} = 7.5 \: kmph$

$\bold{V_{mw} = 7.5 \: kmph}$

Hence, Velocity of man w.r.t water , when boat travels down stream = 7.5 kmph

Answer 2

current of water is
( speed of man in still water - speed of man against current )
= ( 6 - 4.5 ) = 1.5 km/h