You are watching a magic show. for one trick the magician rolls a ball down a hill. suddenly the ball stops moving down the hill .it is as if the ball is defying gravity! come up with the it explanation for how the magician might have accomplished his trick. hint: think of all the forces that might on the ball.

The forces (what causes the ball to accelerate) are gravity, friction, and the normal force. In this case, gravity is a downward force caused by the gigantic mass of the Earth and the mass of the ball. Keep in mind that a force is acceleration. Acceleration is a change in velocity. The ball speeds up. Than it stops speeding up at a certain point where the frictional force (along with air friction) equals the parallel component of gravity. 

Newton's Second Law States- The greater mass of an object, the more force it will take to accelerate the object.

It's because 3 if it was 10 it wouldn't look right do it goes up to 4d