why engine on a motorboat is switched off much ahead of approaching the shore?
give answer in 30-40 words
Answers
Answer:
WHEN THE BOAT IS MOVING, WITH THE HELP OF THE MOTOR, IN OPEN SPACE, THERE IS MUCH MOMENTUM BUILT UP IN THE BOAT. i.e. THE BOAT IS MOVING WITH MUCH VELOCITY. AT THIS TIME, EVEN IF THE MOTOR IS SHUT DOWN, THE BOAT WILL HAVE MUCH MOMENTUM TO COVER SOME DISTANCE, SAY TILL THE SHORE. THEREFORE, THE MOTOR IS SHUT DOWN
Hope it's clear..
Considering the given figure below.
Let v
0
be the stream velocity and v
′
the velocity of motorboat with respect to water. The motorboat reached point B while going downstream with velocity (v
0
+v
′
) and then returned with velocity (v
′
−v
0
) and passed the raft at point C. Let t be the time for the raft (which flows with stream with velocity v
0
) to move from point A to C, during which the motorboat moves from A to B and then from B to C.
Therefore
v
0
l
=τ+
(v
′
−v
0
)
(v
0
+v
′
)τ−l
On solving, we get v
0
=
2τ
l
=3km/hr