GR8 FORCE, WORK, ENERGY, POWER (WEP) by Lizelle Swanepoel

IDENTIFY THE LINK BETWEEN THE GIFS BELOW AND ENERGY CONVERSION

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WHAT IS ENERGY?

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DEFINITION:

Energy is the ability to do work.
Work is Energy transferred.
Also:

Work = The product of force and distance moved by an object.
(NOTE: The force is the component of the force in the direction of motion)

Equation for WORK: W = F x d

Therefor energy and work are interchangeable physical quantities.

E = W (Both have the unit of Joules)

When a system does work, its energy content will decrease.
Conversely, a system on which work is being done will have an increase in its energy content.

WORK

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Definition:

Work = The product of force acting on an object and the distance moved in the direction of the force.
Formula:
W = F.d

Motion of the object must be in the direction of the component of the applied force acting on the object.

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7 Forms of Energy - MRS CHEN (Acronym to memorize)

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Mechanical energy = The Sum of kinetic energy and potential energy.
Kinetic energy is the energy due to an object’s motion.
Potential energy is the energy due to position relative to a reference point.

Radiant (Light) energy = Electromagnetic energy that travels through space as electrical and magnetic waves.
Other types of EM energy include radio waves, microwaves, X-rays and gamma rays.

Sound energy = a form of mechanical energy that starts with a vibration in matter. Sound waves can travel through matter; not through a vacuum (empty space).

Chemical energy = the energy stored in chemical bonds between atoms of a compound. If bonds are broken, energy is released and can be converted to other forms of energy.

Heat energy = the kinetic energy due to moving atoms in a substance.
All matter has thermal energy because atoms in a substance are constantly moving. An object with more mass has greater thermal energy than an object with less mass because it has more atoms.

Electrical energy = the energy of moving electrons.
Electrons flow through wires to create electric current.

Nuclear energy = energy stored in the nuclei of atoms due to the forces that hold the nucleus together.
The energy can be released by splitting nuclei apart and when unstable radioactive nuclei decay.

MECHANICAL ENERGY IN A WATERFALL

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Energy in a Nutshell

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WORKED EXAMPLES: KINETIC ENERGY

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1. A bullet, having a mass of 150 g, is shot with a muzzle velocity of 960 m·s⁻¹. Calculate its kinetic energy.

Solution:
E_K=1/2mv²= 1/2(0,150 )(960 )²= 69 120 J

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PENDULUM PROBLEM

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Do the following problem:
A metal ball of mass 0,2 kg is tied to a light string to make a pendulum. The ball is pulled to the side to a height (A), 0,1 m above the lowest point of the swing (B). Air friction and the mass of the string can be ignored. The ball is let go to swing freely.

Calculate the potential energy of the ball at point A.
Calculate the kinetic energy of the ball at point B.
What is the maximum velocity that the ball will reach during its motion?

Roller Coasters and Mechanical Energy

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1817 - First roller coaster features cars that locked onto the track (Paris)

1885 - “CYCLONE”: 1st Powered Chainlift Roller Coaster; Coney Island, Brooklyn, New York

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ANSWERS

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EXERCISE 1

EXERCISE 1

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Question 2 - SKETCH

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EXERCISE 2

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ROLLER COASTER WORKSHEET

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Roller Coaster Physics

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Energy transformations in a coaster ride:

ROLLER COASTER PROBLEM 1

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Wooden roller coasters: Shiver me timbers

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ROLLER COASTER LAB

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Purpose:

Your goal is to design and build the wildest roller coaster ride that will deliver a marble safely to the end. You must at least demonstrate three successful consecutive runs.

Criteria: Your roller coaster should have at least:

· 2 hills, 2 turns and 1 vertical loop (extra credit for extra loops, hills or turns)

Materials:

· 2 lengths of insulation tubing & marble

· Scissors & toothpicks

· Support material like wooden sticks or paper cups

· Stop watch (phone timer) & meter rule
· Slow motion cellphone video recorder

Procedure:

Design a roller coaster and submit your design for approval before construction.
You need to do Potential energy and Kinetic energy calculations.
For this you need to measure the height of the roller coaster from where the marble starts to the base where the marble ends its trip.
You need to calculate the velocity of the marble as it finally rolls off into a cup.
The entire group must make the demonstration in front of the class and speak on their project (with a video of your team’s experience in building it.)
Class will vote for best themed & decorated roller coaster (2-point bonus).

Calculations:

Mass of marble (kg) = m =
Track Height (m) = h =
Distance traveled_horizontal (m) = d_x =
Time t (s) =
Theoretical final velocity of marble v = √(2gh) =
Actual final velocity (m.s^-1) of marble v = d_x / t =
E_p (J) = mgh =
E_k (J) = ½mv² =
E _Lost (E_p– E_k) =

Conclusion:

When was the first roller coaster made?
Which is the world’s highest coaster?
What do you think happened to the energy that was lost during the marble ride?
Name the law and principle demonstrated during the marble ride.

Roller Coaster Project Rubric:
| Looking For… |

Way
Part Way
No Way

Scoring

| Presentation |

Well presented, covers the history, physics and team experience.
Reading from paper, some parts missing, lacking seriousness.
Missing major parts of presentation or making a joke of presentation.

Physics,History /2
Formal presentation /3

| Roller Coaster |

Has all the appropriate number of hills, loops and/or turns.
3 successful trials in a row | Missing some of the requisite features.
2 successful trials in a row | Missing loop. Trials mostly unsuccessful.

Features /3

| Workmanship & Theme |

Neat finish and well decorated. Has a well defined theme.
Wobbly. Theme is not apparent/ is silly/ is unappealing
No theme, Structure completely unstable

Workmanship /1 Theme /1

| Calculations |

All calculations done correctly.
Some calculations done wrong.
Large errors in calculations.

Calculations /5

| Conclusions |

All questions answered fully and correctly.
Some questions answered correctly or partial answers.
Answers wrong or show lack of understanding.

Conclusions /2

| Teamwork |

Team has worked well together to produce an effective and strong product, with equal distribution of tasks.
Some team members worked harder than others in completing the project.
Most of the work has been done by one or two people.

Effective Teamwork /3

TOTAL 20

SKATEPARK MECHANICS!

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3. A roller coaster ride at an amusement park starts from rest at a height of 50 m above the ground and rapidly drops down along its track. At some point, the track does a full 360° loop which has a height of 20 m, before finishing off at ground level. The roller coaster train itself with a full load of people on it has a mass of 850 kg. 3.1 Draw a sketch of the track in the space below and label any relevant heights above the ground.

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ENERGY ALWAYS CONSERVED

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WHAT IS WORK IN PHYSICS

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WORK = FORCE x DISTANCE

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PRAC: Build your own roller coaster

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DEFINTIONS

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DEFINTIONS

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FORCE = PUSH OR PULL

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NOTES - EXERCISE ANSWERS

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