Potential/Kinetic Energy + Work

Potential Energy: Gravitational (Definition + Examples)

- Energy an object has due to its vertical height position (it is determined by mass and height from surface as well as the force of gravity) - Ski Slope, Book on a shelf, Rock on edge of cliff

Potential Energy: Stored Mechanical (Definition + Examples)

- Energy due to the elastic properties of a substance - Spring, Rubber Bands

Kinetic: Mechanical Energy (Definition + Examples)

- Energy due to the movement of a substance from one place to another - Running, Wind, Water Movement

Kinetic: Electrical Energy (Definition + Examples)

- Energy due to the movement of electrons within atoms - Lightning, Electric Current

Kinetic: Thermal Energy (Definition + Examples)

- Energy due to the vibrations or movement of particles in a substance - Fire, Hand Warmer, Sun

Kinetic: Electromagnetic Energy (Definition + Examples)

- Energy that travels as electromagnetic waves - Infrared Waves, Microwaves, X-rays, Gamma Rays, Ultraviolet, and Visible Light

What is always true in a d-t graph?

- Must always begin at point (0,0), for it is impossible to travel a certain distance within zero units of time - Represents a positive slope

Kinetic: Sound Energy (Definition + Examples)

- The energy due to the vibrations of air molecules - Musical Instruments, Voices

Potential Energy: Chemical (Definition + Examples)

- The energy stored in the bonds of atoms and molecules - Foods and Fuels

Potential Energy: Nuclear (Definition + Examples)

- The energy that holds the nucleus of an atom together - Fusion and Fission

What are five examples of objects that have Potential Energy?

1.) Car parked on top of a hill (GPE) 2.) Fission Reaction at power plant (N) 3.) Unlit Match (C) 4.) Compressed Spring (SM) 5.) Book on top of shelf (GPE)

What are five examples of objects that have Kinetic Energy?

1.) Lit match (Thermal KE) 2.) A car driving down a street (Mechanical KE) 3.) Light bulb (Electromagnetic KE; Light) 4.) Lightning (Electrical KE) 5.) Musical Instruments (Sound KE)

The Human body converts chemical energy into what three forms? Explain.

1.) Mechanical Kinetic Energy; allows us to move around as Human beings( i.e walk, move arms, fingers, etc) 2.) Electrical Kinetic Energy; allows our minds to think and perform various functions through electrical impulses 3.) Thermal Kinetic Energy; helps us maintain body warmth through the fats in which it produces

Can an object that has stored energy do work? Explain.

Yes, for instance, if someone is carrying a box that has gravitational potential energy and drops the box, when the box hits the floor, it does work on the floor. Some of the box's kinetic energy is transferred to the floor. You will hear some of the energy as a loud crash and feel some of the energy near your feet as the energy travels through the floor.

Is a roller coaster an example of a closed system? Provide an example proving why.

Yes; for instance, as a roller coaster travels up a ramp, it slows down, but gains gravitational potential energy

What is velocity (speed)?

the rate at which an object, substance, or particle travels (expressed as the time it takes to cover a certain distance)

What is work?

the transfer of energy from a particle or object to another caused by a force

Define Energy Conversion:

the transfer of energy from one form to another (ex. mechanical KE to electrical KE)

Guided Practice: Explain how a pendulum works

Your hand does work by pushing up the ball when it transfers energy from you to the ball. Subsequently, as the ball's vertical distance from the ground increases, its gravitational potential energy increases as well. When the ball is dropped it has mechanical kinetic energy. Moreover, it does work as well when it pushes against the next ball. This causes the dropped ball to transfer energy to the next ball, and that ball transfers energy to the next ball as it pushes it. The ball then, with mechanical kinetic energy moves upward. However, as the ball's vertical distance from the ground increases, its gravitational potential energy increases as well. Once the ball has no more force going upwards, gravity pulls the ball down as it has mechanical kinetic energy. Eventually, the pattern then repeats itself after the dropped ball hits the next ball.

What is force?

a push or pull

What is a closed system?

a system in which no energy and matter can pass through the system boundary; moreover, energy is transformed and exchanged and the total amount of energy remains constant

What is motion?

a term referring to an object, substance, or particle moving

What is energy?

a term that describes the ability to cause a change

Energy is responsible for causing ___________ in the motions or positions of objects.

changes

What is the equation for calculating average speed?

let v = velocity let d = distance let t = time v = d/t

The faster an object moves or the more mass it has , the _________ kinetic energy the object has

more

If two objects are moving at the same speed, the object with more mass has __________ kinetic energy.

more * Note: in the image, the green ball, when it is dropped with an equal force as the red ball will have more kinetic energy. This is due to the fact that because both balls are dropped from the same height and with equal force, the green ball has more mass than the red ball, and thus it has more kinetic energy.

What is the Law of Conservation of Energy?

states that energy CANNOT be created nor destroyed but rather transformed from one form to another

What is potential energy?

stored energy due to the interactions between objects or particles

Example of Sound to Electrical

Ear detects sound generating electrical impulses in a brain

What does work depend on?

Force and Distance, hence that in order to calculate work it is force x distance

What is the difference between KE and PE?

An object such as a roller coaster after falling down a ramp has Kinetic energy because it is in motion, while a roller coaster at the top of a hill has Potential energy because it is at rest and has predominantly stored energy.

Example of Thermal to Mechanical

Convection Currents (i.e breezes, etc)

What is kinetic energy?

Energy due to motion

Example of Thermal to Chemical

Food being cooked/baked/etc

What is an example of an object having decreasing PE and increasing KE?

Roller coaster traveling down a ramp

Kinetic and potential energy is measured in what?

Joules (J)

What two factors does the kinetic energy of a moving object depend on?

Mass and Speed (as evident in the equation where m = mass and v = speed/velocity)

What two factors does potential energy depend on?

Mass and height

Do all energy conversions create 100% useful energy? Explain with an example.

No; for example, a generator turbine, for instance, is spun to generate electricity, yet not 100% of the mechanical kinetic energy is converted to electrical energy. Rather, some is converted to thermal energy (through friction), sound energy, etc.

What is an example of an object having increasing PE and decreasing KE?

Roller coaster traveling up a ramp

Example of Chemical to Thermal

Oil used to heat a home

At which point will the coaster have its most potential energy? Why?

Point A; it is at its highest distance from the ground, thus, having its most gravitational potential energy

At which point will the coaster have its most kinetic energy? Why?

Point B; after coming down from point A, it would have had its greatest vertical drop, and thus, by point B, it would have been traveling at its greatest velocity (speed)