A focus on Energy Transfer:
Forms of Energy Review
Kinetic (Forms of energy where objects are moving)
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Potential Energy (Energy that is stored - where objects can move but are not)
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Principles of Energy Transfer
Principle No. 1: Energy is conserved.
Principle No. 2: Energy is transformed from one form into another.
Principle No. 3: Usually most forms of energy transfers turn into heat.
Here are a few examples of Energy Transfer:
Principle No. 2: Energy is transformed from one form into another.
Principle No. 3: Usually most forms of energy transfers turn into heat.
Here are a few examples of Energy Transfer:
Energy in a pendulum is converted from Gravitational Potential Energy to Kinetic (Mechanical) and back.
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Energy in a thrown ball is converted from Kinetic Energy to Gravitational Potential Energy. The in between is called Mechanical Energy.
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A Short Discussion on Energy Transfer & Conservation of Energy
Gravitational Potential Energy Transfer to Mechanical
As we hold the object with mass up high, the object has Gravitational Potential energy. Once we let the nail go - we quickly converted it into Kinetic Energy - or energy in motion. Since Kinetic energy is concerned with the objects mass and velocity, the faster the object is falling, the more kinetic energy it has. Therefore, the moment before it hit the can - it had the highest level of kinetic energy.
However, energy can neither be created or destroyed - rather, it is conserved. So where did the energy go? Once the object hit the can - the Kinetic energy was converting into elastic potential energy by crumpling the can. However, since the can is unable to rebound, all of that energy was converted into two other forms of energy - Heat and Sound.
When I demo'd what happens to a can's temperature before and after I crush it with my foot - we witness how the can's temperature rose up to 1-2°C. What that tells us is that when we take a moving object with kinetic energy - and put that energy into an object and crush it - most of that energy was converted into heat and sound, but some of it may or may not have converted into elastic.
Use these video's to witness what happens when you collide two steel spheres with a lot of mass and how kinetic energy is converted into heat energy.
However, energy can neither be created or destroyed - rather, it is conserved. So where did the energy go? Once the object hit the can - the Kinetic energy was converting into elastic potential energy by crumpling the can. However, since the can is unable to rebound, all of that energy was converted into two other forms of energy - Heat and Sound.
When I demo'd what happens to a can's temperature before and after I crush it with my foot - we witness how the can's temperature rose up to 1-2°C. What that tells us is that when we take a moving object with kinetic energy - and put that energy into an object and crush it - most of that energy was converted into heat and sound, but some of it may or may not have converted into elastic.
Use these video's to witness what happens when you collide two steel spheres with a lot of mass and how kinetic energy is converted into heat energy.
Elastic Potential Energy Transfer of a Bow and Arrow
When shooting a bow and arrow, the archer must get his energy from the food he eats - so that he can pull back the bow with the arrow. As he pulls the bow with the arrow back - he's converting chemical potential energy into mechanical energy with his arms and in turn, turns the mechanical energy into elastic potential energy as he pulls back the string. Once he lets go of the string, the bow returns back to it's original position - which is releasing all of the stored elastic energy and is converting it into mechanical energy as it increases the kinetic energy.
Food --> Muscles --> Pulling back the bow --> Letting it go Chemical --> Mechanical --> Elastic PE --> Kinetic/Mechanical |
Gravitational Potential Energy TRANSFERRING to other forms:
QUESTION 1: IF ENERGY IS CONSERVED, WHY DOES IT NOT REACH AS HIGH AS IT DID BEFORE?
Question 2: Where does the energy go after the ball hits the ground?
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Collisions from objects with MECHANICAL ENERGY transfer into both heat and sound
When things collide, we turn mechanical energy into heat. As you clap your hands, notice how warm it gets. In class, I take two massive metal balls and bang them together with a piece of paper in the middle. It creates just enough energy to burn a hole in the paper.
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In this video - watch how students convert Kinetic energy into heat upon impact.
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In this video - this professor shows how even slamming a hammer down on a plastic object converts into heat energy.
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In this video - I show you how crushing a can with your foot increases the heat energy of the can.
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Other Energy transfer scenarios:
The energy from the sun in it's shortest explanation - is nuclear. Nuclear is converted into heat and light. It's the light, through radiation, that reaches the earth. The solar panels then convert that light energy into electricity.
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The wind is a type of mechanical energy, which then turns the turbines - which is another type of mechanical energy. The turbine then converts the mechanical energy into electricity.
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Water behind the dam has gravitational potential energy. As it flows through the dam within the Penstock - it is converted into kinetic (mechanical) energy. As it flows through the Turbine, the attached generator converts mechanical energy into electricity.