Newtons Laws Forces A force is a push

Newton’s Laws

Forces • A force is a push or pull on an object. • Forces are vectors - have magnitude and direction. • Multiple forces applied to an object is the same as the effect of a single force equal to the vector sum of the forces applied.

Newton’s First Law • An object at rest will remain at rest and an object in motion will continue in motion in a straight line at constant velocity unless the object experiences an external force. • Often called the law of inertia.

Newton’s First Law • Inertia is the resistance of an object to changes in motion. • The measure of the inertia of an object is mass. • The more mass an object has the greater the resistance to changes in motion.

Inertia at Work

Newton's Second Law • The net force acting on an object equals the product of the mass and the acceleration of the object. • The direction of the force is the same as that of the acceleration.

Newton's Second Law

Newton's Second Law

Force = mass x acceleration F=ma

Force = mass x acceleration F=ma

Weight • Weight (W) is the force of Earth’s gravitational attraction to a body. • The acceleration is the acceleration due to gravity, g = 9. 8 m/s 2 or 32 ft/s 2 • The magnitude of the gravitational force acting on an object of mass (m) near the Earth’s surface is called the weight of the object W= mg

Newton’s Third Law • When one object exerts a force on another object, the second object exerts a force of the same magnitude but in the opposite direction on first. • Often stated as “For every action there is an equal and opposite reaction.

• The action and reaction forces act on different objects • The action force is the balloon pushing the air out. • The reaction force is the air pushing the balloon forward.