A boat goes across a river with a velocity 12 km/h . The magnitude of its resultant speed in flowing water is 13 km/h . The velocity of water flow in the river is

Question

A boat goes across a river with a velocity 12 km/h . The magnitude of its resultant speed in flowing water is 13 km/h . The velocity of water flow in the river is (A) 5 km/h (B) 7 km/h (C) 9 km/h (D) 1 km/h

Tardigrade Admin · Accepted Answer

Resultant speed vbr= vb + vr vbr = √vb2 + vr2 (13)2 = (12)2 + vr2 vr2 = 169 - 144 Velocity of water in the river vr = √25 = 5 km/h

Q. A boat goes across a river with a velocity $12 km / h$ . The magnitude of its resultant speed in flowing water is $13 km / h$ . The velocity of water flow in the river is

5 km/h

7 km/h

9 km/h

1 km/h

Resultant speed $v_{b r} = v_{b} + v_{r}$
$v_{b r} = v_{b}^{2} + v_{r}^{2}$
$(13)^{2} = (12)^{2} + v_{r}^{2}$
$v_{r}^{2} = 169 - 144$
Velocity of water in the river
$v_{r} = 25 = 5 km / h$

Q. A boat goes across a river with a velocity 12km/h . The magnitude of its resultant speed in flowing water is 13km/h . The velocity of water flow in the river is