Posted by Rychelle on .
Salmon often jump waterfalls to reach their breeding grounds. One salmon starts 2m from a waterfall that is 0.55m tall and jumps at an angle of 32°. What must be the salmon's minimum speed to reach the waterfall?

Physics 
drwls,
The range R of the jump must be R = 4m, if the waterfall were not there. That correspopnds to a distance to maximum height (the waterfall top) of 2 m.
Using the equation for range:
(R/2) = (1/2)*Vo^2*sin(2A)/g = 2 m
Vo^2 = 21.8 m/s
Vo = 4.7 m/s
A is the launch angle. It gets doubled because 2sinA*cosA = sin(2A) appears in the equation for R.