Reaching Maximum Height??????

Question

A long jumper leaves the ground at an angle of 20.0 degrees to the horizontal and at a speed of 11.0m/s.

(a.) How long does it take for him to reach maximum height?

(b.) What is the maximum height?







I'm stuck on how to do these. Thanks for the help!!!!! God Bless!

Answer 1

The time to apogee is when vy(t)=0
vy(t)=11*sin(20)-9.81*t
a) set vy(t)=0 and solve for t
t=0.384 seconds

b) y(t)=11*sin(20)*t-.5*9.81*t^2
solve for y(0.384)
0.721 m

BTW: the time to apogee is 1/2 the total flight time when resistance is ignored. to solve for the range plug 2*0.384 into the following equation
x(t)=11*cos(20)*t


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