Forces Physics- Ms. Jeffrey

The meaning of force Force- A push or a pull on an object resulting from an interaction with another object. Forces only exist as a result of an interaction. The unit of Force is the Newton [N] Force is a vector quantity Two types of forces Contact forces Action-at-distance forces

Contact forces Contact forces- result when the two interacting objects are physically contacting each other. Examples Frictional Force Tension Force Normal Force Air Resistance Force Spring Force Applied Force

Friction Force Force exerted by a surface as an object moves across it. This force opposes the motion of an object. Two types: Static The frictional force that keeps an object at rest This force must be overcome to get an object to start moving. Kinetic The frictional force that slows an object down The object is already in motion.

Tension force The force that is transmitted through a rope or cable when it is pulled tight by forces acting in opposite directions. Pulling force

Normal force Support force exerted on an object by a surface If two objects are not in contact, they cannot exert a normal force on each other. What would happen if there was no normal force?

Air resistance force Special type of frictional force that acts on objects as they travel in air Opposes the motion of an object (just as friction does on a surface) Pushes against a moving object What are some examples of air resistance?

Spring force Force exerted by a compressed or stretched spring upon an object Restores the object back to rest, or equilibrium

Applied Force A force that is applied to an object by a person, or another object Pushing or pulling an object What are some examples of applied forces?

Action-at-a-distance forces Action-at-a-distance forces- result when two interacting objects are not in physical contact. They still apply a push or pull on other objects Examples Gravitational Force Magnetic Force Electrical Force

Gravitational force The force with which a massive object attracts another object towards itself Which direction does gravity act? The force of gravity is equal to the weight of an object To find the force of gravity, use the equation: Fg = m*g Where g= -9.8 m/s2 and m=mass of object MASS AND WEIGHT ARE NOT THE SAME Mass is the amount of matter an object has Weight is related to the pull of the Earth on an object If an object’s mass is 2 kg, what will it’s mass be on the moon?