Go Back   Physics Help Forum > High School and Pre-University Physics Help > Kinematics and Dynamics

Kinematics and Dynamics Kinematics and Dynamics Physics Help Forum

Reply
 
LinkBack Thread Tools Display Modes
Old Sep 20th 2019, 01:24 PM   #1
Junior Member
 
Join Date: Sep 2019
Posts: 3
Yacht problem

The entrance to a harbour is a channel of length A which runs between two banks a distance B apart. The banks and the channel can be assumed to be rectangular. There is a current flowing with a speed v from one bank to the other. A yacht travelling at a constant speed relative to the water u wants to enter the harbour.

Find the minimum value of u for the yacht to safely enter the harbour. Express u in terms of v,A and B

Need help solving this. I keep getting told we cannot assume the yacht is perpendicular to the water flow
Physics77 is offline   Reply With Quote
Old Sep 22nd 2019, 05:05 AM   #2
Senior Member
 
Woody's Avatar
 
Join Date: Jun 2016
Location: England
Posts: 1,060
The velocity of the yacht must be such that over the distance A the current v will push it sideways by the distance B.
Find the (equation for the) time taken for the flow v to push the yacht a distance of B
find the (equation for the) speed (along the channel) required for the yacht to move the Distance A in that time.
This gives you (the equations for) two (perpendicular) velocities
add (the equations for) these two velocities to get the (equation for the) total velocity of the yacht.
__________________
~\o/~

Last edited by Woody; Sep 22nd 2019 at 05:08 AM.
Woody is offline   Reply With Quote
Reply

  Physics Help Forum > High School and Pre-University Physics Help > Kinematics and Dynamics

Tags
problem, yacht



Thread Tools
Display Modes



Facebook Twitter Google+ RSS Feed