Aball has a speed of 15 m/s. only one external force acts on the ball. after this force acts, the speed of the ball is 7 m/s. has the force done positive, zero, or negative work on the ball?

Negative work

Explanation:

The work-energy theorem states that the work of the resultant forces acting on a particle modifies its kinetic energy:

Since the mass of the ball has to be positive, the work is negative.

since you're a real machine, your ama is always less than your ima, because you can never totally eliminate friction.

i think it's 35 meters