Physics projectile word problem? Help please? 10 points

I'm getting frustrated. I feel that I used the formulas correctly and that I'm going through the right reasoning, so why do I suck at getting these? PLEASE HELP

A projectile is fired at 65.0° above the horizontal. Its initial speed is equal to 150.0 m/s. Assume that the free-fall acceleration is constant throughout and that the effects of the air can be ignored. What is the maximum height reached by the projectile?

The initial vertical component of velocity = 150sin(65.0°) = 135.95m/s.

In a vertical direction :
Initial vertical component of velocity, u = +135.95m/s (taking upwards as positive)
Acceleration = g = -9.81m/s²
Final vertical component of velocity, v =0 (at max height)
Max height = s

Use the standard constant-acceleration equation|:
v² = u² +2as (or vf² = vi² + 2as if you use those symbols)
0² = 135.95² +2 x (-9.81) x s
s = 135.95²/19.62
= 942m

If you are struggling with projectile calculations try the video-lessons below.

Look up the SUVAT equations. You will DEFINITELY NEED TO LEARN THEM.
Only force pulling down is gravity (9.81m/s) which is represented as 'g', and which replaces the 'a' (acceleration) in the suvat's.

Initial velocity = 150 m/s
Final velocity (when at max height) will be ZERO.


As the balls going up, gravity is negative,

should be able suss it from that i think

The initial velocity upward, the only important bit is 150 sin 65.0°. We can ignore the horizontal, 150 cos 65.0° bit.

Now, d = ½at^2 and v = at. So t = v/a and ½a(v/a)^2 = ½v^2/a = d. Or h in our case. So h = ½(150sin65.0°)^2/9.81 = 942 meters

Edit: Significant figures.

Vi is 150.0 m/s
so
Viy = sin(65) (150.0) = 135.95 m/s
then
Vyf^2 = Vyi*2 + 2 g d
(final upward V at top of arc is 0)
0 = 135.95^2 + 2(-9.81)d
d = 6.93 m