Starting downstream, 3.33 m away from a waterfall 0.287 m in height, at what minimum speed must a salmon jumping at an angle of 25.2 ◦ leave the water to continue upstream? Answer in units of m/s.

Answer 1

You want to take the x(t) equation: v₀cos(θ₀)t = x and solve for t in terms of x.

You then want to sub that into the equation for y = v₀sin(θ₀)t - (1/2)gt² in order to eliminate t and get a function of y and x, and v₀. This equation will be solvable for v₀ as only one term will have v₀ in it and x,y are known for the top of the waterfall.