Physics Final Exam

Physics

study of laws that describe (not explain) the behavior and energy

Scientific law

a statement that describes an observable event. Describes the what and helps make predictions about an event, does not explain why

Theory

the how and why, tested but may change

Frame of Reference

3D space with a fixed point from which all motion can be measured (motion is observed differently from different frames of reference)

Relative Velocity

velocity from the perspective on one body using that body as the frame of reference. It is the difference in velocities between the two bodies

Law of Inertia

an object in motion or at rest stays at rest until acted on by a force (mass is the measure of inertia in a body, mass is NOT the same as weight)

Mechanics

the study of motion

Kinematics

study of HOW objects move

Dynamics

study of force and WHY objects move

Distance

how far an object has traveled

Displacement

change in position or how far an object is from it's starting point (X = X2 - X1)

Force

need to change the state of motion of a body

Average Acceleration

change in velocity per unit of time

Instantaneous Velocity

Displacement per an infinitely small change in time

Uniform Motions

body is moving with a constant velocity

Uniform Acceleration

body is moving with constant acceleration

Vector

quantity with both magnitude and direction (think vector from despicable me)

Scalar

quantity has magnitude, but no associated direction (ex. speed, time)

Rectangular Form

vector is composed of an x-component and a y-component

Polar Form

vector is the magnitude and direction

Heading

motion in which an object is set to go (ex. airspeed of an airplane)

Track

motion in which the object travels with respect to a fixed point

Projectile

free body that moves above the ground with gravity as the only force that acts on it (neglecting air resistance)

Newton's 1st Law

Law of Inertia, 'Every object continues in its state of rest or of uniform velocity in a straight line, as long as no net force acts on it.'

3 States of Motion

rest, moving with constant velocity or accelerated motion

Balanced Force

When the net forces equals zero; free body is either at rest or moving with constant velocity

Unbalanced Force

When the net force does NOT equal zero; object has accelerations

Newton's 2nd Law

F=ma

Weight

force of gravity on a free body

Normal Force

acts perpendicular to the surface of contact and often balances out weight

Newton's 3rd Law

'Whenever one object exerts a force on a 2nd object, the 2nd exerts an equal force in the opposite direction on the first'

Friction

the force that acts in the opposite direction as the applied force; 2 frictions: kinetic (object in motion) and static (object is at rest)

Statics

study of objects at rest

Torque

tendency for a force to rotate an object around some point, called the fulcrum (axis of rotation)

Law of Balanced Torques

when an object is not accelerating in a rotational way, the sum of the positive and negative torques is zero

Static Equilibrium

requires 2 conditions (all forces must be balanced & all torques must be balanced)

Momentum

mass x velocity, sometimes described as an objects inertia in motion

System

group of objects

Isolated System

no external forces act

Impulse Momentum Theorem

states that impulse equals the change in momentum

Centripetal Force

keeps an object on a circular path, it is center-seeking force

Centripetal Acceleration

result of velocity constantly changing direction as an object travels a circular path, points to the center of circle

Period

time required to complete a full revolution

Frequency

number of revolutions in one second

Centrifugal

NOT A REAL FORCE

Banking

reduces the need for friction between the tires and the road by making the normal force contribute to the centrifugal force

Newton's Universal Law of Gravitation

can be used to calculate gravitational force between planets and minuscule changes in Earth's gravity depending on location or altitude

Kepler's 1 Law

Planets move in elliptical orbits around the sun

Kepler's 2 Law

Planets cover the same area of space in the same amount of time

Kepler's 3 Law

Planet's orbital period is proportional to the size of its orbit

Work

Describes when a force acts on an object and the object moves some distance

Energy

ability to do work

Kinetic Energy

energy in motion

Work-Energy Principle

links work and energy; the net work done on an object is equal to the objects change in kinetic energy

Potential Energy

the potential to do work on its position relative to its surroundings

Conservative Force

any force for which work is independent of it's path

Nonconservative Force

any force for which depends on the path

Elastic Potential Energy

when a spring is stretched or compressed

Law of Conservation of Energy

states that total energy is neither increased nor decreased in any process; energy can be transformed and transferred but the total amount remains constant

Power

rate at which work is done or energy is transferred

Efficiency

ratio of power output to power input

Electric Force

microscopic; it is the force that holds things together at the atomic level

Static Electricity

net electric charge which produces attractive or repulsive effect

Charges

positive or negative; like charges repel & unlike charges attract

Law of Conservation of Electric Charge

'The net amount of electric charge produced in any process is 0' OR 'No net electric charge can be created or destroyed'

Insulators

materials that do not carry electric charge

Conductors

transfer electric charge

Semiconductors

have properties somewhere in between insulators and conductors

Coulomb's Law

microscopic version of the Law of Gravitation and - except that the electric force may be attractive or repulsive

Voltage

difference in charge between terminals

Current

2 terminals are connected by a conductor, electrons flow

Ohm's Law

describes the relationship between voltage, current, and resistance

Resistance

measure of how much a material resists electric current flow