2/6 PotU: Video review for energy transformations and forces

photo showing riders on a roller coaster going down a steep hill

Warm up

Sketch the following roller coaster, then draw energy bar charts for Position A, B, and C.

image showing roller coaster with A at the top of a hill, B at the top of the the second, lower, hill, and C and D along a flat portion lower than the second hill.

No stamp today, but you will get credit for completing the warmup section for today.

Lesson

Video day. What the main video and answer the questions on the handout. You may ask the sub to pause the video if you need time to complete lengthier questions.

File Name: Roller-Coaster-Physics-video-notes.pdf

Other energy videos you may enjoy

Is energy conserved on a galactic scale? Watch the videos below:

01/16 PotU: Sound energy

Notes from today

Image of inner ear.
The cochlea contains the nerves that resonate at different sound frequencies (notes).
  • Metronome: A device that keeps the rhythm; aka the “beat”
  • The shorter something is, the faster it vibrates.
    • We had a demonstration of the vibrating bar from the fall final; the shorter the bar was, the faster it vibrated.
  • Both string and wind instruments depend on lengthening or shortening the material that the sound is produced by to create different notes.
    • In some cases, the string is thicker (lower notes) or thinner (lower notes).
  • Our ears have hearing nerves: The long ones detect low notes, and the short ones high notes.
    • As we get older, our short cells tend to die off more than our long ones, so kids and teenagers can often hear sounds that adults can’t
    • A dog whistle is similar: The frequency is so high that people can’t hear it, but dogs can.

Sound is the rhythmic motion of air particles. So, similar to thermal energy, it is a type of kinetic energy.

Humans are said to be able to hear from 20 to 20,000 Hz (cycles per second). Test your hearing range with the video below. (I can hear from about 60 to 13,000 Hz.)

When the ball hits the tuning fork:

  • Kinetic (ball moving towards tuning fork) moves from the ball into
  • Sound energy from the tuning fork.

The video below shows a tuning fork being lowered into a glass of water, shot with a very high speed cameras (about 50 times faster than most cell phone cameras, and even faster than the slow-mo option on phone cameras).

Sample instruments

In the instruments below, notice how the length and/or thickness changes to make a range of notes.

Piano

Image of strings in a grand piano
Notice the long, thick strings on the left side (top in this photo) for the lower notes, and the short, thinner strings on the right (bottom in this photo).
The longer strings are placed above the shorter ones for space efficiency.

Trombone

Navy band trombone setcion
Trombones have a section that can slide in and out to make the tube length longer or shorter.

Clarinet

Two clarinets
Clarinet players place their fingers over the wholes in the instrument to make the effective tube length shorter. The lowest note is will all wholes covered.
Flutes and recorders use a similar system.

Percussion instruments

Percussion instruments
Percussion instruments come in all shapes and sizes. The larger ones generally produce lower notes.

Ukulele

Soprano ukulele
The ukulele has two thick strings in the middle, and outside strings are thinner.

1/15 AP Phys: Conservation of energy with springs & ramps

Learning objectives

The student is able to describe and make qualitative and/or quantitative predictions about everyday examples of systems with internal potential energy. (Science Practices 2.2, 6.4, and 7.2)

Introduction

Observe the demonstration and take notes on your observations and questions. Think about/answer the following questions:

  • If the track were steeper or shallower, how would the motion change? Justify your answer using your knowledge of kinematics and energy.
  • Short answer on our own (2 minutes).
  • Expand answer with our group (3 minutes) .
  • Expand answer with the class (5 minutes) .

Equipment

  • Low friction cart
  • Ramp
  • Meterstick
  • Stopwatch
  • Assorted masses

Tools

photo of a clinometer on a sloped surface displaying angle in degrees.
Clinometer measures the angle of a slope.
  • Calculator
  • Clinometer to measure angle of ramp
  • Whiteboard for sharing group work
  • Books or other objects to change the steepness of the track

Safety

  • Please keep carts on tables to prevent people from slipping on them (or damaging them).
  • The carts have spring plungers; make sure they aren’t compressed near delicate parts of your body, or breakable objects.
  • Think and be careful

Design and conduct an experiment to answer the following question.

  • If the track were steeper or shallower, how would the motion change? Justify your answer using your knowledge of kinematics and energy.

Keep focused on your objective!

Provide detailed procedural steps. Make sure that if you gave them to someone who had not completed the lab, they could do everything completely and in the same way your group did it.

Why are you doing each step, and what are reasonable measurements.

Are you completing these steps as you progress?

  1. Prelab notes
  2. Title
  3. Purpose
  4. Personal procedures/ideas
    • Group procedures/ideas/notes
  5. Class procedures/ideas/notes
  6. Data table
  7. Notes on experiment from as you conduct it.
  8. Scatter plot or other visual analysis of data.
  9. Processing/analyzing data:
  10. Group conclusion (what can your group conclude, without looking at other groups’ data?)
  11. Whiteboard notes
  12. Class data comparison and conclusions.

01/8-13 AP Physic: Energy

Wednesday & Thursday, Jan 8 & 9

We added energy equations and the work work/energy theorem to our energy knowledge. In physics, work is used to add or remove energy from a system.

Class/homework: Page 151, # 9-18

Friday, Jan 10

We worked on an energy simulation using the PhET Energy Skate Park simulation. You can see the assignment here, and the simulation here:

Monday, Jan 13

We started learning about power. Textbook Section 5.6, pages are 142-146. Solve problems 48-54 on page 154.