Answer:
5 m
Explanation:
When a projectile is launched at an angle of 30 degrees,
the vertical component is exactly half the magnitude of the initial velocity.
Thus, the vertical component is 10 m/s.
Since it takes 1 second for gravity to steal about 10 m/s from the upward velocity,
the projectile will reach its highest point after traveling for one second
at an average speed of 5 m/s
(i.e., assuming an upward velocity that drops linearly from 10 m/s to zero).
Thus, the maximum height is 5 m.