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Arada [10]
2 years ago
6

A hunter wishes to cross a river that is 1.5 km wide and flows with a velocity of 5.0 km/h parallel to its banks. The hunter use

s a small powerboat that moves at a maximum speed of 12 km/h with respect to the water. What is the minimum time for crossing?
Physics
1 answer:
anzhelika [568]2 years ago
6 0

Answer:137.48 s

Explanation:

Given

Width of river=1.5 km

velocity of river=5 km/h

velocity of boat w.r.t river =12 km/h

To cross the river in minimum time hunter needs to cross the river perpendicular to the flow

i.e. velocity of boat w.r.t  water must be perpendicular

i.e. x component of boat must be equal to river flow

12cos\theta =5

where \theta is angle made by boat w.r.t bank

cos\theta =\frac{5}{12}

cos\theta =0.416

\theta =65.417^{\circ}

its vertical component is 12sin(65.417)=10.91 m/s

Time taken=\frac{1.5\times 1000}{10.91}=137.48 s

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