How can I solve this please help?

Question

A 19.0-kg cannonball is fired from a cannon with muzzle speed of 1 200 m/s at an angle of 38.0° with the horizontal. A second ball is fired with the same initial speed at an angle of 90.0°. Let y = 0 at the cannon.

(a) Use the isolated system model to find the maximum height reached by each ball.

h first ball	=  ____ m
h second ball	=  ____ m

(b) Use the isolated system model to find the total mechanical energy of the ball–Earth system at the maximum height for each ball.

E first ball	=  ____ J
E second ball	=  ____ J

Answer 1

(a)

First ball

Voy = 1200sin38 = 738.8 m/s

When maximum height is reached Vy = 0

Assume free fall acceleration of gravity

a = -9.81 m/s^2

2a ( y-yo) + Voy^2 = Vy^2

Yo = 0

2ay + Voy^2 = 0

Y = -Voy^2/-2a

Y = - ( 738.8)^2/-2*9.81 = 27819.8 m

Second ball

2a(y-yo) + Voy^2 = Vy^2

Voy = 1200

2ay + Voy^2 = 0

y = -Voy^2/2a = -1200^2/(2*9.81)

y = 73394 m

(b)

first ball

E = mgh = 19 * 9.81 *27819 = 5,185,341 J

second ball

E = mgh = 19 * 9.81 * 73394.5 = 13,680,000 J