A 0.150 kg baseball is thrown upward with an initial speed of 20.0 m/s. what is the force on the ball when it reaches half of its maximum height

Since we are ignoring air resistance, the only force acting on the ball will be the force of gravity.

According to Newton's second law:

F = ma where:

m is the mass of the ball = 0.15 kg

a is acceleration due to gravity = 9.8 m/sec^2

Substitute to get the force as follows:

Force = 0.15 * 9.8 = 1.47 Newton