Chapter 2: Forces and Motion

The acceleration of a falling object is due to the force of gravity between the object and the Earth.

Every falling object must deal with air resistance Every falling object must deal with air resistance. This is the opposing force of air that a falling object must overcome. Air resistance opposes downward motion.

Around 1665 and 1666, Sir Isaac Newton developed 3 laws that describe all forms of motion- rest, constant motion, and accelerated motion.

Newton’s First Law of Motion Objects at rest tend to stay at rest, objects in motion tend to stay in motion unless an outside force acts upon them. The tendency of an object to remain in motion or stay at rest is called inertia. Inertia is similar to momentum.

Newton’s Second Law of Motion The acceleration of an object depends on the mass of the object and the force applied

Formula: Force = Mass x Acceleration   Force is measured using Newtons (N). Answer = 50.0 Newtons

Newton’s Third Law of Motion For every action, there is an equal and opposite reaction. All forces come in pairs. Every force must have an equal and opposite force.

All moving objects have momentum All moving objects have momentum. Momentum depends on the mass of the object and the velocity with which it is traveling.

Formula: Momentum = Mass x Velocity   The unit of momentum is kilogram-meters per second, kg-m/sec

Conservation of Momentum The total momentum for a group of objects will remain the same unless an outside force acts upon the objects. One object may lose momentum, but this momentum will be gained by another object. Momentum is always conserved!