DAY 65
Goals: SWBAT...
1. Write & understand the equations for Total Mechanical Energy
2. Understand the relationship between work and power
3. Solve basic work & power problems
Warm-Up (4min): The Flow of Mechanical Energy
Read, then complete.
Mechanical energy is the energy that is possessed by an object due to its motion or due to its position. Mechanical energy can be either kinetic energy (energy of motion) or potential energy(stored energy of position).
An object that possesses mechanical energy is able to do work
A classic example involves the massive wrecking ball of a demolition machine. The wrecking ball is a massive object that is swung backwards to a high position and allowed to swing forward into building structure or other object in order to demolish it. Upon hitting the structure, the wrecking ball applies a force to it in order to cause the wall of the structure to be displaced. The diagram below depicts the process by which the mechanical energy of a wrecking ball can be used to do work.
Give three more examples of scenarios in which an object uses mechanical energy to do work
CLASSWORK
1. 065A: Total Mechanical Energy Notes
The Total Mechanical Energy
As already mentioned, the mechanical energy of an object can be the result of its motion (i.e., kinetic energy) and/or the result of its stored energy of position (i.e., potential energy). The total amount of mechanical energy is merely the sum of the potential energy and the kinetic energy. This sum is simply referred to as the total mechanical energy (abbreviated TME).
TME = PE + KE
As discussed earlier, there are two forms of potential energy discussed in our course - gravitational potential energy and elastic potential energy. Given this fact, the above equation can be rewritten:
TME = PEgrav + PEspring + KE
The diagram below depicts the motion of Lee Ben Fardest (esteemed American ski jumper) as he glides down the hill and makes one of his record-setting jumps.
Look at the starting and ending energies. Is energy conserved in this example?
The total mechanical energy of Lee Ben Fardest is the sum of the potential and kinetic energies. The two forms of energy sum up to 50 000 Joules. Notice also that the total mechanical energy of Lee Ben Fardest is a constant value throughout his motion. There are conditions under which the total mechanical energy will be a constant value and conditions under which it will be a changing value. This is the subject of Lesson 2 - the work-energy relationship. For now, merely remember that total mechanical energy is the energy possessed by an object due to either its motion or its stored energy of position. The total amount of mechanical energy is merely the sum of these two forms of energy. And finally, an object with mechanical energy is able to do work on another object.
2. 065B: How Does Work...Work?
Let's learn about the relationship between Work & Power: https://ed.ted.com/on/5bau54uF#review
Read questions 1-9
Watch the video and answer the questions/solve the problems
Discuss :-)
3. Preread the lab (Chapter 10 pg 274-275: LINK).
List the four materials required to do the lab (hint, only three are written, but one big obvious one is in the picture)
At Home Learning (HW)
1. Complete all 9 questions/problems from #065B
If you got stuck, ask a classmate, or contact me via the Remind App
2. 065C: Wednesday we will continue with Power: Watch/take notes/complete edPuzzle on the following:
3. 065D: Weigh yourself. Calculate your mass in kg (2.2lb = 1kg)
4. 065E: Preread the lab (Chapter 10 pg 274-275: LINK).
List the four materials required to do the lab (hint, only three are written, but one big obvious one is in the picture)
Essential Question: How can I show that energy cannot be created or destroyed, but CAN be transported from one place to another, and CAN be transferred between systems?
#Goals: SWBAT...
1. Draw scaled graphical models of energy for an object at a specific position using your energy equations.
2. Use your energy model and equations to solve energy related problems.
5. Evaluate claims regarding roller coaster designs using evidence and reasoning from your energy model and the sim to support your conclusion.
Standards
That there is a single quantity called energy is due to the fact that a system’s total energy is conserved, even as, within the system, energy is continually transferred from one object to another and between its various possible forms. ((HS-PS3-1), (HS-PS3-2)
Conservation of energy means that the total change of energy in any system is always equal to the total energy transferred into or out of the system. (HS-PS3-1)
Energy cannot be created or destroyed, but it can be transported from one place to another and transferred between systems. (HS-PS3-1)
The availability of energy limits what can occur in any system. (HS-PS3-1)
Warm-Up (4min):
Find the energy for the following objects:
1. a 10kg object at 15m height and zero velocity
2. a 10kg object moving at 5m/s at zero height
3. a 10kg object moving at 5m/s at 15m height
4. a 10kg object moving at 10m/s at 5m height
CLASSWORK
1. Quiz
2. Conservation of Energy at the Skate Park
Note: Mechanical Energy is KE and PE. Friction causes a reduction in KE, but is not a form of Mechanical Energy
Link to Simulation: http://phet.colorado.edu/sims
WARM-UP
Quote: “If a tree falls in the forest and there’s no one there to hear it, does it make any sound?”
Question (answer in complete sentences): How do sounds get created? How do they travel?
CLASSWORK
Today's agenda is on a slideshow: : LINK