Question

you throw a ball at 37 degrees above the horizontal and you want to hit a target on the ground, 20 ft from where you are standing. how fast should you throw the ball? what will be its final velocity?

Answer 1

I assume that the target is equivalent to the height of the ground.
First you need to take into account the gravity, which is 9.8m/s^2.
Second, you also need to calculate the vertical velocity resulting from the angle at which the ball is thrown, which is 37 degrees from the ground. For the height, use the sine.
xsin(37), x being the velocity at which the ball is thrown, will be what you are looking for.

Then pick an appropriate kinematic equation that accounts for both the horizontal velocity and vertical velocity, and vertical displacement being 0, and horizontal displacement being 20 ft. Note that the x sine(37) will be what you need to calculate the original vertical velocity, and that way you can also use x to calculate the speed at the initial angle.

Let me know if you have any further questions, I will be happy to walk you through if desired.