A long jumper leaves the ground at an angle of 20 degrees and travels a horizontal distanceof 7.0m before landing. What is the takeoff speed of the jumper?

To be honest I really don't know how to solve it. A step-by-step explantion would be helpful.

1 answer

Horizontal:
7=viCos20*timeinair
timeinair=7/Vicos20

Vertical:
hf=hi+ViSin20*t-4.9t^2
put the timeinair expression in for time
0=0+ViSin20(7/cos20)-4.9(49/cos^2 20)

compute Vi