When Sam presses the brake lever, a pair of rubber shoes clamps onto the metal inner rim of the front and back wheels. As the brake shoes rub against the wheels, friction is caused and the kinetic energy possessed by the vehicle is converted into heat which slows down the vehicle.
If you increase the mass m of the car, the force F will increase, while acceleration a is kept constant. Because F and m are directly proportional.
If you increase the acceleration a of the car, the force F will increase, while mass m is kept constant. Because F and a are directly proportional.
How can Newton's laws be verified experimentally; is by setting this experiment, and changing one variable while keeping the other constant, then observe the change in F.
Hope this helps.
Motion by definition is the movement of things above or below the surface of gravity
