DAY 60
#Goals: SWBAT...
1. Write & understand the equations for Kinetic and Potential Energy
2. Set an appropriate reference (zero) line.
3. Solve KE and PE problems
Warm-Up (4min): Review KE and PE from the learning at home videos
1. Write the equation for Potential Energy (PEg)
2. If you're measuring the PEg of a basketball being thrown above the ground, which location of the reference (zero) line makes the most sense?
i. setting the line at the ball's highest possible position?
ii. setting the line at the ball's lowest possible position?
iii. setting the line at the average of the ball's lowest and highest positions?
3. Write the equation for Kinetic Energy (KE).
4. If you double the velocity of an object, the KE value quadruples. If instead, you triple the velocity, what happens to the value of the KE? Hint: think about what the v2 part of the equation means....
5. Is PEg a vector or scalar? What about KE?
answers to the warm up are below the HW section
CLASSWORK
1. #060A: Potential Energy: Notes
Definition: Potential energy is the stored energy of position possessed by an object.
What does that mean? There is a direct relation between gravitational potential energy and the mass of an object. More massive objects have greater gravitational potential energy. There is also a direct relation between gravitational potential energy and the height of an object. The higher that an object is elevated, the greater the gravitational potential energy.
Equation: PEg = mass • gravity • height
or... PEg = m • g • h
In the above equation, m represents the mass of the object, h represents the height of the object and grepresents the gravitational field strength (9.8 N/kg on Earth) - sometimes referred to as the acceleration of gravity
Check for Understanding: If you double the height of an object, what happens to the PEg?
2. #060B: Kinetic Energy: Notes
Definition: Kinetic energy is the energy of motion
The kinetic energy of an object is directly proportional to the square of its speed.
That means that for a twofold increase in speed, the kinetic energy will increase by a factor of four. For a threefold increase in speed, the kinetic energy will increase by a factor of nine. And for a fourfold increase in speed, the kinetic energy will increase by a factor of __________. The kinetic energy is dependent upon the square of the speed.
Equation: KE = 1/2 • m • v2
where m = mass of object
v = speed of object
You can often trade KE for PE, and vise versa. We'll learn more about that kind of Conservation of _________ tomorrow
3. #060C: PEg and KE Practice Problems
1. A cart is loaded with a brick and pulled at constant speed along an inclined plane to the height of a seat-top. If the mass of the
loaded cart is 3.0 kg and the height of the seat top is 0.45 meters, then what is the potential energy of the loaded cart at the height of the seat-top?
2. If a force of 14.7 N is used to drag the loaded cart (from previous question) along the incline for a distance of 0.90 meters, then how much work is done on the loaded cart?
***Note that the work done to lift the loaded cart up the inclined plane at constant speed is equal to the potential energy change of the cart. This is not coincidental! More on Mechanical Energy, and how energies change from one type to another...tomorrow. ***
3. Determine the kinetic energy of a 625-kg roller coaster car that is moving with a speed of 18.3 m/s.
4. If the roller coaster car in the above problem were moving with twice the speed, then what would be its new kinetic energy?
5. Missy Diwater, the former platform diver for the Ringling Brother's Circus, had a kinetic energy of 12,000-J just prior to hitting the bucket of water. If Missy's mass is 40-kg, then what is her speed?
6. A 900-kg compact car moving at 60 mi/hr has approximately 320 000 Joules of kinetic energy. Estimate its new kinetic energy if it is moving at 30 mi/hr. (HINT: use the kinetic energy equation as a "guide to thinking.")
At Home Learning (HW)
1. Complete all problems from #060C
If you got stuck, answers and more help are here at these links:
2. #060D: Tuesday we will cover Conservation of Mechanical Energy: Watch/take notes/complete EdPuzzle on the following:
(8:26) Notes: Introduction to Conservation of Mechanical Energy with Demonstrations - EDpuzzle
Warm-Up Answers
1. KE=mgh
2. iii. lowest
3. KE = 1/2mv2
4. multiply the original KE by 32, or 9
5. Energy is always a SCALAR
EMERGENCY LESSON PLAN / ASSEMBLY THROW AWAY LESSON PLAN
Essential Question: What would require the most work and energy: driving a car up a gently-sloped hill or driving a car up a steep hill to the same summit?
#Goals: SWBAT...
1. Solve work problems
2. Learn about common misconceptions in thermodynamics
3. Predict which block will fly higher
4. Find cool science influencers/Youtubers to follow - #nerdparty
Warm-Up (3min)
Answer the Essential Question above. Explain your answer with a sentence or two
CLASSWORK
1. Work time + Review 059C
2. TODAY IS ALL ABOUT DEBUNKING MISCONCEPTIONS
Which is colder? Plastic, or aluminum? Which one would melt ice faster?
Which block with fly higher. The one shot in the middle, or the one shot closer to the edge?
You have an option today. You can just enjoy the videos, and relax
Or, you can write down 3+ interesting observations for each video, and share them out to the class, for extra credit
https://www.youtube.com/watch?v=vqDbMEdLiCs&index=2&list=PL772556F1EFC4D01C
Want to know why that happened with the blocks?
Learning at Home (HW)
Edpuzzle: https://edpuzzle.com/media/5824d3f752251eea3e26cda4
Unit Goals: What is a wave? How do they act? How are do waves differ?
Goals: SWBAT...
1. Define a "standing wave"
2. Label the components of a wave
3. Define wave-related terms
Warm-Up (5min):
1. What is a standing wave?
2. Copy the wave pictured on the board, then label each of the components
standing wave demo with nodes (pivot points)
CLASSWORK
1. Questions on #059A: Waves on a String (8min)
Directions:
1. Open Waves on a String: https://phet.colorado.edu/en/simulation/wave-on-a-string
2. With the Oscillate button on and with No End checked, investigate waves more carefully using the Amplitude slider.
Write answers to the following after your group has talked about each and agreed.
a) Define Amplitude in everyday language.
b) Explain how the wave behaves as the Amplitude changes using the characteristics you described in the warm-up
c) Use a rope/string/ on the floor for some investigations and explain how you could change the Amplitude of a wave.
3. Repeat step number 2, for Frequency, Tension and Damping.
4. Set Amplitude on high, Frequency to .25Hz, Damping on none, and Tension on low. Also, have on Oscillate, Timer and No End. Use the Pause button to freeze the wave.
a) Place a blank piece of paper on your monitor and trace the wave and the wave generator. Mark the green balls. This is a vertical position- horizontal position graph, label your axes.
b) Quickly press Play, and then Pause again. Use the same piece of paper, put it on the monitor and make sure to get the generator in the same spot. Trace the new wave.
c) Write about the differences and similarities in the characteristics. You may have to do some more tests by pressing Play, then Pause and tracing to test your ideas.
5. Same settings as above in #4. Set Amplitude on high, Frequency to .25Hz, Damping on none, and Tension on low. Also, have on Oscillate, Timer and No End. Use the Pause button to freeze the wave.
a) Measure the vertical location of a green ball with a ruler. B) Record the vertical position and time.
b) Quickly press Play, then Pause repeatedly to make a data table the vertical position of the green ball versus time.
c) Make a graph of vertical position versus time.
d) Write about the differences and similarities between vertical position- horizontal position graphs (from step 4) and vertical position-time graph you just made.
6. Investigate how waves behave when the string end is Fixed and Loose with Manual settings. Discuss the behavior with your partners, or think about it on your own. Test your ideas and the write a summary.
7. Read to find out what a standing wave is, investigate how to produce one with the simulation and write a procedure that another student could follow to produce a standing wave. Links on standing waves are immediately below:
http://www.physicsclassroom.com/class/waves/Lesson-4/Traveling-Waves-vs-Standing-Waves
http://www.physicsclassroom.com/class/waves/Lesson-4/Formation-of-Standing-Waves
2. #060A: "What is a Wave?" Reading/Notes
The link to the reading is below. While reading, define the terms listed, or answer the questions I've given.
What is a Wave?
a. To introduce a wave to a slinky, what must you do to the first coil in the slinky? (hint, there are four options - list them all)
b. Define "wave" (see end of second paragraph)
c. What is the difference between a pulse and a wave?
What is a Medium?
d. Define "medium"
e. How is the function of the wave medium (to carry the wave) similar to the function of the news media?
f. What is the medium of a stadium wave?
Particle-to Particle interaction
g. In a wave, if the first particle (in a slinky, this would be the first coil) is disturbed upwards, what would happen to the second (next) coil?
A Wave Transports Energy, not Matter
h. In the stadium wave, what happens to the particles (the fans) after the wave passes? How is this similar to a water wave?
i. "energy transport phenomenon" In a slinky wave, how does energy get transferred from the first coil to the last?
Link is here ----> LINK
Wave Demo with Slinky
3. #060B: Check Your Understanding
Answer the five questions below:
1. TRUE or FALSE: In order for John to hear Jill, air molecules must move from the lips of Jill to the ears of John.
2. Curly and Moe are conducting a wave experiment using a slinky. Curly introduces a disturbance into the slinky by giving it a quick back and forth jerk. Moe places his cheek (facial) at the opposite end of the slinky. Using the terminology of this unit, describe what Moe experiences as the pulse reaches the other end of the slinky.
3. Mac and Tosh are experimenting with pulses on a rope. They vibrate an end up and down to create the pulse and observe it moving from end to end. How does the position of a point on the rope, before the pulse comes, compare to the position after the pulse has passed?
4. Minute after minute, hour after hour, day after day, ocean waves continue to splash onto the shore. Explain why the beach is not completely submerged and why the middle of the ocean has not yet been depleted of its water supply.
5. A medium is able to transport a wave from one location to another because the particles of the medium are ____.
a. frictionless
b. isolated from one another
c. able to interact
d. very light
At Home Learning (HW)
1. Complete #060A & B
2. I'm checking #059A tomorrow (Thursday) with an oral quiz. I'll ask you two questions about the simulation activity. Questions could be...
....how does frequency change with an increase in amplitude?
....how does the wave pattern change with an increase in damping?
....compare & contrast the vertical position- horizontal position graphs (from step 4) and vertical position-time graph
....how are standing waves created?
3. Quiz Friday on waves, (wavelength, frequency, amplitude, their interactions, plus medium, plus how waves interact (the video from day 57), etc)