Kinematics in Two Dimension-Niagra falls

[pstfleur]

Kinematics in Two Dimension-Niagra falls(not solved)

1. Suppose the water at the top of Niagra falls has a horizontal speed of 2.7 m/s just before it cascades over the edge of the falls. At what vertical distance below the edge does the velocity vector of the water point downward at a 75 degree angle below the horizontal.



3. Ok so i know the intial and final velocity in the x direction is equal to 2.7m/s with a 0 acceleration.. when it falls I assume that its initial velocity in the y direction is 0?(let me know if I am wrong here), and the acceleration to that is 9.8...now i need to figure out the time to get my Vfy, but I think i need My final position in order to calculate time. please help.

 

[Kurdt]

Yes, you'd assume the y component of velocity is zero as it drops initially. What is key here is the resultant velocity vector being at 75 degrees below horizontal. You know the x component so you need to find the y component that will give that angle to the resultant. Then you can find the vertical distance.