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Standard XII

Physics

Relative Velocity

A boat travel...

Question

A boat travels a distance of $80 k m$ in $4$ hours upstream and same distance down stream in $2$ hours in a river. Then the velocities of boat and stream are (in Kmph)

20, 10

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30, 10

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30, 20

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None of these

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Solution

The correct option is A $30, 10$
Let $v_{b}, v_{r} b$ e the speed of boat and river respectively
$v_{b} + v_{r} = \frac{80}{4} = 20 \dots (1)$
$v_{b} - v_{r} = \frac{80}{2} = 40 \dots (2)$
solving we get $v_{b} = 30, v_{r} = 10$

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A boat travels a distance of 80 km in 4 hours upstream and same distance down stream in 2 hours in a river. Then the velocities of boat and stream are (in Kmph)

The correct option is A 30,10Letvb,vrbe the speed of boat and river respectivelyvb+vr=804=20…(1)vb−vr=802=40…(2)solving we get vb=30,vr=10

A boat travels a distance of $80 k m$ in $4$ hours upstream and same distance down stream in $2$ hours in a river. Then the velocities of boat and stream are (in Kmph)

The correct option is A $30, 10$
Let $v_{b}, v_{r} b$ e the speed of boat and river respectively
$v_{b} + v_{r} = \frac{80}{4} = 20 \dots (1)$
$v_{b} - v_{r} = \frac{80}{2} = 40 \dots (2)$
solving we get $v_{b} = 30, v_{r} = 10$