Question

Question: A projectile is launched at 30 m/s at an angle of 30 degrees above the horizon. Find its maximum height (a) using energy, (b) using motion equations.

Answer 1

The vertical speed if the projectile is V = 30 m/s * sin 30

V = 15 m/s where V is the vertical speed of the projectile

Energy:

m g H = 1/2 V^2

H = V^2 / (2 * g) = 15^2 / (2 * 9.80) = 11.5 m

Motion:

We can use time to fall H since the rise time must equal the fall time

t = 15 / 9.80 = 1.53 sec time to reach 15 m/s

H = 1/2 g t^2 = 1/2 * 9.8 * 1.53^2 = 11.5 m