Motion & Forces: Newton’s Laws of Motion P. Sci. Motion & Forces: Newton’s Laws of Motion

Force What causes an object’s position to change. A push or a pull. Copy This Force What causes an object’s position to change. A push or a pull.

Force cont. Net force = the combination of all forces acting on an object. If 0 (they cancel out) the object does not move or it moves at a constant velocity. (balanced force)

Force cont. If not 0 the object will move in the direction of the net force. (unbalanced force) If there is a net force, acceleration will take place. Either the object will change direction or change speed.

Newton’s 1st Law Copy This An object at rest remains at rest, an object in motion remains in motion unless acted on by an unbalanced force.

1st Law AKA Law of Inertia Copy This Inertia – the tendency for an object to resist a change in motion.

Newton’s 2nd Law The unbalanced force acting on an object equals the object’s mass times its acceleration

Force is measured in Newtons (N) Copy This 2nd Law AKA F = ma Force is measured in Newtons (N) 1N = 1kg x m/s2 Ten times as much.

Newton’s 3rd Law Copy This For every action force, there is an equal and opposite reaction force.

AKA Law of Action/Reaction Newton’s 3rd Law When you sit in your chair, your body exerts a downward force on the chair and the chair exerts an upward force on your body.

Consider the propulsion of a fish through the water Consider the propulsion of a fish through the water. A fish uses its fins to push water backwards. In turn, the water reacts by pushing the fish forwards, propelling the fish through the water. The size of the force on the water equals the size of the force on the fish; the direction of the force on the water (backwards) is opposite the direction of the force on the fish (forwards).

Momentum (p)= mass x velocity Copy This Property of moving objects resulting from its mass and velocity. Comes from Newton’s Third Law Momentum (p)= mass x velocity p=m x v