Motion, Forces, and Energy

Forces force: is a push or pull; is measured in newtons; causes an object to accelerate, and can change the direction of an objects motion.

Applied force: An applied force is a force that is applied to an object by a person or another object. If a person is pushing a desk across the room, then there is an applied force acting upon the object. The applied force is the force exerted on the desk by the person

Frictional force: The friction force is the force exerted by a surface as an object moves across it or makes an effort to move across it. There are at least two types of friction force - sliding and static friction. Example:

Forces that Act on Objects Gravity Friction Drag Lift Thrust

Motion Affects Position Direction Speed Acceleration

Newton’s Law’s of Motion

Newton’s First Law States: An object at rest stays at rest unless an unbalanced force acts on it. *An object moving in a straight line at constant speed will continue doing that unless acted on by a force. This force is called friction. It is a force that resists motion between 2 surfaces that are in contact. It always acts opposite to the direction of motion. Sir Isaac Newton

Inertia is the tendency to resist a change in motion * Inertia is the tendency to resist a change in motion. * The more mass (amount of matter in an object) an object has, the greater the inertia. ** Example: A toothpick has less inertia than a pencil because it has less mass.

Newton’s Second Law * States: A net force changes the velocity of the object and causes it to accelerate. *The more mass or inertia an object has, the harder it is to accelerate. More mass = less acceleration ** Example: pushing a refrigerator vs. pushing a grocery cart

Newton’s Third Law States: Forces always occur in equal but opposite pairs. In other words, for every action, there is an equal and opposite reaction. ** Example: A rocket blasting off Space Shuttle Columbia

Types of Energy Potential Kinetic Thermal