Question

While trying to explain a physics concept a student said stuff keeps doing what its doing unless something messes with it what law was this student summarizing

Answer 1

Newton's first law of motion: Also called the law of inertia, states that "An object at rest remains at rest, or if in motion, remains in motion at a constant velocity unless acted on by a net external force"

According to Newton's second law "the force (F) acting on an object is equal to the mass (m) of an object times its acceleration (a)", meaning that when the soccer player kicks a ball, a force is acting on the ball, therefore increasing it's acceleration. After the force is applied, the gravity and the resistance of air will be the ones in charge of stopping the ball.

Baseball: The ball changes direction and speed when it's hit with the bat.

Bowling: When the ball hits the pins, the change from being at rest to a higher velocity.

Wrestling: The wrestler exerts a force on the oponent increasing or decreasing it's velocity.

The jet airplane has more inertia. Inertia is the resistance of an object to move if at rest, or to change its velocity and it is proportional to the mass of the object. Therefore, the jet airplane being heavier than the car will have more inertia. It has to be clear that it is not due to the fact that is at rest that is the one with more inertia, but mostly related to the mass. If the example was with two cars, one at constant velocity and the other at rest, both with the same mass, the one with greater inertia will be the one moving.

No, forces do not always cause motion. They have to be greater than the forces that oppose movement, such as friction, air resistance or gravity.