Motion, Speed, Velocity, and Acceleration

Subject Orientation

• Motion is relative, meaning an object is moving if its position relative to a fixed point is changing.
• Speed describes how fast an object is moving, and is calculated as distance over time.
• Velocity describes how fast and in what direction an object moves; it's also known as directed speed.
• Acceleration is the rate at which velocity changes.
• Accelerating in the direction of velocity speeds an object up.
• Accelerating against velocity slows an object down.
• Accelerating at an angle to velocity changes its direction.
• Acceleration is calculated as the change in velocity over a time interval.

Uniform Motion & Uniformly Accelerated Motion

• Uniform Motion (UM) occurs when an object's velocity is constant, with zero acceleration and no change in direction.
• An object is in UM if it covers equal distances in equal time intervals.
• Uniformly Accelerated Motion (UAM) happens when the value of acceleration is constant and non-zero.
• In UAM, the velocity changes at a constant rate.
• An object is in UAM when its velocity changes by the same amount in equal time intervals.
• Gravity is the force of attraction between objects with mass, pulling objects toward each other or towards the Earth.

UAM Equations Variables

• Vf = final velocity which is the velocity of an object at the end of its motion.
• Vi = initial velocity which is the velocity of an object at the start of its motion.
• a = acceleration with is the rate of change of velocity over time.
• t = time which is the duration over which motion occurs.
• d = distance/displacement which is the total length traveled/the shortest path from start to end.

UAM Equations

• Vf = Vi + at
• d = Vit + (1/2)at^2
• Vf^2 = Vi^2 + 2ad
• d = ((Vf + Vi)/2) * t

Projectile Motion

• Projectile motion is experienced by an object or particle projected in a gravitational field and consists of horizontal and vertical motion.
• Gravity primarily affects projectile motion.
• Trajectory: the path a moving object follows through space.

Equations for Projectile Motion:

• y = gt^2/2
• x = Vixt
• Y = viyt + gt^2/2

Impulse & Momentum

• Momentum is the product of mass and velocity (p = mv).
• Momentum measures an object's inertia in motion and indicates how difficult it is to stop the object.
• Impulse is the change in momentum caused by a force applied on a moving object over time, represented.
• The direction of impulse is the same as the direction of the net force applied on the object.
• Momentum can be changed by applying force or extending the time over which the force is applied.
• Impulse-Momentum Theorem: The change in momentum of an object during a time interval equals the impulse of the net force acting on it.
• The Law of Conservation of Momentum states that the total momentum of a system remains constant if no external forces act on it.
• (m1V1 + m2V2)initial = (m1V1 + m2V2) final

Types Of Collision

• Elastic Collision: both momentum and kinetic energy are conserved. The objects bounce off each other without losing kinetic energy to heat, sound, or deformation.
• Inelastic Collision: momentum is conserved, but kinetic energy is not. Some kinetic energy is lost as heat, sound, or deformation and the objects may still bounce off, but with less speed than before.

Conservation Of Mechanical Energy

• Mechanical energy is the energy an object possesses due to its motion or position.
• Mechanical energy can be kinetic (energy of motion) or potential (stored energy of position).
• Potential energy is the stored energy of position possessed by an object. Energy that is stored and held in readiness because in the stored state it has the potential for doing work.

Types Of Potential Energy

• Elastic Potential Energy: the energy stored in elastic materials.
• Chemical Potential Energy: energy of position at the submicroscopic level.
• Gravitational Potential Energy: the energy stored in an object as a result of its vertical position or height. Calculated using the formula: PE = mgh

Kinetic Energy

• Kinetic Energy: the energy of motion.
• An object that has motion – whether it is vertical or horizontal motion – has kinetic energy.
• Calculated using the formula: KE = 1/2mv^2

Heat, Work, & Efficiency

• Heat is the transfer of thermal energy from one object or system to another due to a temperature difference.
• Heat Transfer: The process by which thermal energy moves from a region of higher temperature to a region of lower temperature through the three types of heat transfer.
• Conduction is the direct transmission of heat or electricity through a substance when there is a difference of temperature or of electrical potential between adjoining regions
• Convection is the movement within a fluid caused by hotter, less dense material rising and colder, denser material sinking.
• Radiation is the emission of energy as electromagnetic waves or moving subatomic particles.
• Work: transferring energy to an object by applying a force that causes movement or displacement.
• Efficiency: the ratio of useful output energy (or work) to total input energy, measuring how effectively energy is converted into useful work.

Generation, Transmission, and Distribution of Electrical Energy

• An electric power system, also known as an electric grid, is a large network of interconnected power generating plants connected to consumer loads.

Three Stages Of Electric Power Supply:

• Generation: transformation of energy (thermal, kinetic, or chemical) into electrical energy (13,200 to 24,000 volts). Dangers include explosions and burns from equipment failures.
• Transmission: sending electricity over long distances. Voltage is increased to 138k to 765k volts at transmission substations using Step-Up Transformers. Another substation reduces the voltage to 34.5k to 138k volts with Step-Down Transformers for distribution.
• Distribution: delivering electricity to homes and businesses. A distribution substation reduces the voltage to 2,400-19,920 volts.

Generating Stations

• Generating Stations: also known as power plants - facilities where other forms of energy (heat, kinetic, chemical) are converted into electrical energy.
• Geothermal: Uses heat from the Earth.
• Hydroelectric: Uses energy from falling or fast-running water.
• Thermal: Uses steam from heated water.
• Diesel-power: Burns fossil fuels like diesel.
• Coal power: Burns coal to produce steam.
• Power lines are high-voltage lines that carry large amounts of electricity.
• Distribution lines are lower-voltage lines that carry electricity from substations to consumers, and distribution transformers reduce voltage to 120-240 V for safe use.