Forces Notes

1)force: 2)Newton (N): 3)net force: Key Terms Is a push or pull. A force is described by its magnitude and by the direction in which it acts. The SI unit for the magnitude, or strength, of a force. The combination of all forces acting on an object. The net force determines if an object moves and in which direction.

4) unbalanced forces: 5)balanced forces: 6)friction: Key Terms When acting on an object it results in a net force and causes a change in the object’s velocity. An objects velocity does not change when acted on by balanced forces. Is a force acting in opposite direction of the motion of an object. It is the force that two surfaces exert on each other when they move past each other.

7)static friction: 8)sliding friction: 9)rolling friction: Key Terms Friction that acts on stationary objects. You must use extra force to start an object moving and overcome static friction. Occurs when two solid surfaces slide over each other. Friction that results when an object rolls across a surface.

10)Fluid friction: Key Terms Occurs when a solid object moves through a fluid (e.g. sky diver, and swim diver).

Important Thing About Friction The strength of the force of friction depends on the types of surfaces involved and on how hard the surfaces push together. What is the cause of friction?

11)Gravity: 12)Mass: 13)Weight: Key Terms Is a force that pulls objects toward each other. The measure of the amount of matter in an object. The SI unit of mass is the kilogram (kg). The gravitational force exerted on a person or object at the surface of a planet.

More on Gravity The force of gravity between objects increases with greater mass and decreases with greater distance.

Don’t be confused about gravity, mass & weight. Weight is a result of the force of gravity, whereas mass depends on how many & the type of atoms that make up something. Mass generally doesn’t change unless you loose an arm. Weight = Mass x Acceleration due to gravity