friction
The force that causes the ball to fall to the ground is gravity. Gravity is a natural force that attracts objects towards each other, and in the case of the ball falling, it is being pulled towards the Earth's center by the force of gravity.
The resistance the ground has on the ball causes it to slow down and this force is called friction. Ice has little friction which is why the ball would have rolled further on ice for instance.
Gravity is the force which makes a thrown ball fall back to the ground. It is the force which attracts all objects to the Earth.
The initial velocity of a dropped ball is zero in the y (up-down) direction. After it is dropped gravity causes an acceleration, which causes the velocity to increase. F = ma, The acceleration due to gravity creates a force on the mass of the ball.
The force pulling objects back towards the Earth is gravity.
Because space is extremely curved in proximity to the huge mass of the earth. Or because the force of gravity causes attraction between the ball and the Earth. It depends on which aspect of physics you are using.
Gravity.
The transfer of energy from your racket and the ground to the ball causes its particles to move faster, which causes heat.
gravity's force pulls it back
No, when a ball is hit on the ground, the runners must try and advance to the next base.
An outside force causes an object to have more momentum. For example, if you push a ball, the ball would have more momentum and would therefore move. You pushing the ball would be the outside force.
Friction - between the surface of the ball, and the ground.