A) The acceleration is due to gravity at any given point if you look at it vertically, so

.
b)

, so

. We use

and then the final speed must be 0 because it stops at the highest point. So

. Solve for

and you get

c)

, and then we plug the values:

and we already have the time from "b)", so
![Y_m_a_x = [(32sin(25))*(32sin(25)/10)] - 5(32sin(25)/10)^2](https://tex.z-dn.net/?f=Y_m_a_x%20%3D%20%5B%2832sin%2825%29%29%2A%2832sin%2825%29%2F10%29%5D%20-%205%2832sin%2825%29%2F10%29%5E2)
; then we just rearrange it
![Y_m_a_x = 10[(32sin(25))^2/100] - 5 [(32sin(25))^2/100]](https://tex.z-dn.net/?f=Y_m_a_x%20%3D%2010%5B%2832sin%2825%29%29%5E2%2F100%5D%20-%205%20%5B%2832sin%2825%29%29%5E2%2F100%5D%20)
and finally
Frequency = velocity/wavelength
Frequency = 10/20
Frequency = 0.5 Hz
The answer is it stays constant.
light travels fastest through a vacuum which means "empty space, void"