A ball is thrown up into the air. Ignore air resistance. When it is rising and reaches half of its maximum height, the net force acting on it is

The net and only force acting on the ball thrown up into the air at half of its maximum height is the weight  of the ball

Explanation:

When the ball is rising in the air, the force, F, acting on it is given by the product of the mass, m × acceleration, a

The acceleration of a body thrown in the air = Gravitational acceleration = g = Constant

Therefore;

The force acting on the body thrown in the air F = Constant = m × g (downwards)

The force acting on the ball thrown up into the air at half of its maximum height = The mass of the ball × The acceleration due to gravity = The weight  of the ball.