| A | B |
|---|
| Centrifugal force | a force pulling outward from the center of rotation |
| Centripetal force | a force pulling inward toward the center of rotation |
| Kinetic friction | the force of friction when two objects are rubbing against each other in motion |
| Magnitude | refers to size of a vector |
| Vector | any physical quantity that is defined by size and direction |
| Static friction | friction which keeps things still |
| Force | Push or pull |
| Acceleration | measure of how fast velocity is changing; time rate of change |
| Constant acceleration | when the acceleration of an object is non-changing |
| Constant free-fall | near the surface of the earth, all objects fall with constant acceleration |
| Constant speed | an object with unchanging speed |
| Free fall | an object is free-falling when only gravity is the force pulling it down |
| Inclined plane | a flat surface which has a slope |
| Negative distance | when an object travels in the opposite direction of the beginning of path |
| Negative velocity | an object moving back along the direction of space |
| Scalar | a quantity that has a size or magnitude only |
| Velocity | the speed and direction of motion |
| Relative motion | motion which a nonmoving person sees, but the moving person does not see |
| Weightlessness | no force of gravity on an object |
| Consant velocity | when speed and motion remain the same |
| Gravity | an attractive force between two objects in the universe |
| Inertia | the tendency of objects to resist changes in speed or direction of motion |
| Law of Gravity | two bodies attract each other with the force proportional to the product of the bodies' mass |
| Mass | quantity of matter |
| Newton's 1 Law | Inertia-objects at rest tend to stay at rest and objects in motion tend to stay in motion |
| Newtons 2 Law | the more force in an object, the more it accelerates |
| Newton's 3 Law | every action has an equal and opposite reaction |
| Universal gravity | a constant pull of gravity |
| Projectile | an object initially propelled by a force outside itself and keeps moving |
| Friction | the force that resists motion of one object rubbing against another |
| Energy | a physical quantity of work |
| Kinetic energy | the energy of an object by virtue of its motion |
| Potential energy | the energy an object has by virtue of its position in a force field like gravity (stored energy) |
| Work | force times distance; work is energy |
| External force | a force that acts on a system from the outside |
| Internal force | a force that acts from one part of a system on another part of the same system |
| Momentum | quantity of motion |
| Collision | when two or more objects come into contact |
| Elastic collision | when two objects bounce apart with no loss of kinetic energy ; if kinetic energy is conserved |
| Inelastic collision | when some of the initial kinetic energy of two colliding objects converts into heat |
| Elasticity | a measure of how springy an object is |
| Angular velocity | the rate of the angle turning with time |
| Lever arm | the perpendicular distance from the center of rotation |
| Precession | when the axis of a rotating object moves in a circle |
| Torque | a twisting force (force times lever arm) |
| Uniform circular motion | when a moving object is acted upon by a force perpendicular to its motion |
| Chemical energy | the energy released or absorbed as a result of a chemical reaction |
| Fictitious force | one's inertia resisting friction (like in cars) |
| Distance | a linear interval of space |
| Accelerometer | the instrument used to measure acceleration |
