Hey guys I am a bit confused with a problem on relative velocity (1 Viewer)

[bleakarcher]

http://exampapers.web.fc2.com/tests/hs/y11/physics/2002BlakehurstHSMovingAboutTopicTest.pdf

For Q2 of the above paper is the velocity of the boat relative to the ground 8 m/s north? Confused with what the velocities are relative to. Can someone tell me how to determine this?

 

[Fizzy_Cyst]

For Q2(a) It would be 8ms-1 North -- you need to think about the frame of reference. The water is already moving at 15ms-1W, so relative to the water, the only movement is the movement North. Think about if there were two boats on the water and one of the boats started moving North, from the perspective of the other boat -- all it is doing is moving North, as both boats are moving at the same speed to the West.

For part (b) The ground itself is stationary (hopefully), so the movement relative to the stationary ground includes BOTH the West component and the North component. You will need to use pythagoras and trig to determine magnitude and direction.