A boat moves at 6.50 m/s relative to the water. (You can neglect relativity at t

Question

A boat moves at 6.50 m/s relative to the water. (You can neglect relativity at these slow speeds.)

Part A

Find the boat's speed relative to shore when it's traveling downstream in a river with a 1.5 m/s current.

Express your answer to two significant figures and include the appropriate units.

Part B

Find the boat's speed relative to shore when it's traveling upstream in a river with a 1.5 m/s current.

Express your answer to two significant figures and include the appropriate units.

Part C

The boat travels 100 m downstream and then 100 m upstream, returning to its original point. Find the time for the round trip.

Express your answer to two significant figures and include the appropriate units.

Part D

Compare this time with the round-trip time if there were no current.

Explanation / Answer

boat's speed relative to shore Vbs = Vbw + Vws

given Vbw = 6.5 m/s

Vws = 1.5 m/s

Vbs = 6.5 + 1.5 = 8 m/s <<<<<-------answer

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part B

boat's speed relative to shore Vbs = Vbw + Vws

given Vbw = 6.5 m/s

Vws = -1.5 m/s

Vbs = 6.5 - 1.5 = 5 m/s <<<<<-------answer

===========================

for down stream

t1 = d/Vbs = 100/8

for upstream

t2 = d/Vbs = 100/5

total time T1 = t1 + t2 = 100/8 + 100/5 = 32.5 s   <<<<<-------answer

=============

part D

if there were no current t1 = t2 = d/Vbw = 100/6.5

total time T2 = 2*100/6.5 = 30.8 s

T1/T2 = 32.5/30.8 = 1.06   <<<<<-------answer

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