Question

a long jumper jumps at a 20 degree angle and attains a maximum altitude of .6m. What is her initial speed?

Answer 1

Use the kinematic equation:
v^2 = v^2 + 2as
and use it in the y-direction, (in the vertical direction.)
the left v = 0 because the velocity going up is at 0 when they are at their peak.
the right v is the initial velocity, but in the y-direction
a is acceleration, and in the y direction, its gravity, so, 9.8
s is the change in height, in our case, we will use it as the peak height of 0.6m

make sense?