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