Question

A river 400 m wide is flowing at a rate of 2.0 m/s. A boat is sailing at a velocity of 10 m/s with respect to the water, in a direction perpendicular to the river. (a) find the time taken by the boat to reach the opposite bank. (b) how far from the point directly opposite to the starting point does the boat reach the opposite bank ? Concept of Physics - 1 , HC VERMA , Chapter "Rest and Motion : Kinematics

Answer 1

Solution :
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Velocity of boat perpendicular to river =u=10 m/s
Width of river= 400m
time =distance/speed
time=400/10=40 sec
∴40 secs is the  time taken by the boat to reach the opposite bank.

b) In 40 sec time boat will go downstream at a speed =2m/s
so boat will reach opposite bank distance= speed x time
=2x40=80 m from the point directly opposite to starting point.

Answer 2

Explanation:

Velocity of boat perpendicular to river (VB)=10 m/s

Width of river= 400m

(Since time =distance/speed)

time=400/10=40 s

So 40 s will be the time taken .

Now, in 40 s boat will go downstream at 2m/s

so boat will reach the bank .

(Since Distance= speed x time)

=2x40=80 m from the point opposite to initial point.

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