Newton’s 1st Law: The law of inertia. Inertia is an objects tendency to resist changes in motion. An object at rest stays at rest until acted upon by an unbalanced force. The same is true of an object in motion. It will stay in motion until acted upon by an unbalanced force. Motion usually stops due to the forces gravity, or friction. In empty space, moving objects just keep going and going and going because there aren’t forces like air resistance or gravity to stop them!

Newton’s 2nd Law: Force = mass x acceleration. This law tells us that force is directly related to mass and acceleration. In other words, more massive objects require more force to accelerate the same distance as less massive ones. It will also require more force to increase the acceleration of an object. Lastly, we can solve for any of these variables if we are given two of them. Mass = force ÷ acceleration. Acceleration = force ÷ mass.

Newton’s 3rd Law: For every action there is an equal and opposite reaction. Forces come in pairs, so when we send a baseball flying with a force of 50 Newtons, there is also a 50 Newton force acting on the baseball bat in the opposite direction. This is even true when things are sitting still. Gravity pulls down on an object, while the normal force pushes up in the equal and opposite direction.

The answer is Newton's 1st law because the friction of the grass is an unbalanced force which changes the motion of the ball.

Newton’s 1st Law: The law of inertia. Inertia is an objects tendency to resist changes in motion. An object at rest stays at rest until acted upon by an unbalanced force. The same is true of an object in motion. It will stay in motion until acted upon by an unbalanced force. Motion usually stops due to the forces gravity, or friction. In empty space, moving objects just keep going and going and going because there aren’t forces like air resistance or gravity to stop them!

Newton’s 2nd Law: Force = mass x acceleration. This law tells us that force is directly related to mass and acceleration. In other words, more massive objects require more force to accelerate the same distance as less massive ones. It will also require more force to increase the acceleration of an object. Lastly, we can solve for any of these variables if we are given two of them. Mass = force ÷ acceleration. Acceleration = force ÷ mass.

Newton’s 3rd Law: For every action there is an equal and opposite reaction. Forces come in pairs, so when we send a baseball flying with a force of 50 Newtons, there is also a 50 Newton force acting on the baseball bat in the opposite direction. This is even true when things are sitting still. Gravity pulls down on an object, while the normal force pushes up in the equal and opposite direction.