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2/7 AP Phys: Analyzing data

Image showing carts and photogates

Data collection

Please finish data collection for both collisions an explosions. Remember that an explosion uses the spring on one cart, and both carts start with zero momentum.

Data analysis

Analyze all your trials, calculating the momentum and kinetic energy changes for each scenario. If you would like, you can use a Google spreadsheet template here.

Each member of the group needs to make their own spreadsheet. If you prefer to use Excel, you can download the Google Sheet as an Excel spreadsheet.

Homework

Complete all the data analysis in a spreadsheet, and develop a conclusion about the conservation of momentum and kinetic energy in each of your scenarios.

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2/7 PotU: Designing your mousetrap car

cover image for mousetrap car video

Warm up

Using physics, explain why the first hill on a roller coaster always the highest.

Designing your mousetrap car

Next week you will build, test, and the mousetrap car. As you build it, you will also determine the work done by the mousetrap spring by measuring the force and distance the mousetrap arm moves.

Watch the following videos, and take notes about ideas that techniques you may use for your car (we will start with materials on Monday).

Record your notes in today’s exit ticket area and the “Three things I learned this week” section of your bookends sheet.

Before you leave today, turn in your bookends sheet (make sure your name is on it!)

Homework

Start thinking about how you might customize your mousetrap car. Each group will receive the following items, extras are are up to you. If you want to use special materials, collect them over the weekend so you can use them on Monday.

  • One small mousetrap (larger rat traps are not allowed)
  • A light board about 8″ long by 3″ wide (you may replace this if you prefer a different design)
  • Dental floss or similar string
  • One set of plastic wheels with axle
  • One pair of CDs
  • Hot glue
  • Paint stirrer stick (two lengths available), to extend your mousetrap bar and tie your string to.

More videos you might want to view

Another video showing many student-built mousetrap cars.

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1/23-24 AP Phys: Energy practice problems in your textbook

Homework/classwork

Thursday

Page 152, Problems 21-24

Friday

Page 153, Problems 33, 35 (both spring energy), 47 (a red, make sure to do drawings before you start!), 29, 30, 32, 34, 43

Jackson suggests you do Problems 73 and 75; I guess I’ll have to try these this weekend 🙂

Questions? Post them below. Don’t forget, you can log in with just about any social network and receive email updates when your question is answered.

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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.
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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.