Free Fall Frenzy: Penny Myth Busted?

We recently viewed the Mythbusters "Penny Drop" episode. If you missed it in class or wanted to view it again, you should be able to view it at one of the following two links:

• MetaVideo blog


• DailyMotion.com

The episode tested out a physics free fall question we had discussed and calculated in class:
Can a penny dropped from the Empire State Building kill a person?

Knowing only the height of the Empire State Building (381 meters) and that acceleration due to gravity affects all object at a rate of 9.81 meters per second (we round up to ten to make calcuations easier), we calculated that the penny would fall for 8.73 seconds if we didn't factor in friction due to air resistance (which results in objects having a terminal velocity), and that it would hit the ground at a speed of 87.3 meters per second.

If you missed it in class, watch the video, answer ALL of these questions, hand it in and it will count as an extra quiz grade. This offer applies to students who viewed the video in class as well.

Mythbusters Penny Drop Video Questions:

1. According to the show, what is the terminal velocity of a person?
2. What happens to the pennies when the skydiver releases them?
3. What top speeds do their “complex” calculations predict as the terminal velocity of a penny?
4. How does Adam test this prediction?
5. What device does Jamie use to accelerate the penny to that speed?
6. What should Jamie have done before testing the device for the first time?
7. How long does it take the penny to travel the three feet from the device to the concrete block?
8. What velocity do they actually use for their experiment?
9. Why is ballistic gel used to build the Norma, the test dummy’s head?
10. Where do most coins thrown from the observation deck of the ESB end up?
11. According to the experiment, can a penny traveling at terminal velocity penetrate concrete or asphalt?
12. According to the experiment, can a penny traveling at terminal velocity penetrate a human skull?
13. From how far away is the penny fired at Adam’s hand? Does it break the skin?
14. What device do they use to find out how fast a penny has to go to do serious damage?
15. What speed does the penny reach? How many times the speed of sound is that?

If you cannot view the video, ask Mr. Barkan to bring the DVD player at lunchtime and you can view it then. You MUST ask in advance and you MUST allow at least 20 minutes to view the video.

The Plane Truth

We recently used the launching of paper airplanes (we used index cards in class) to develop our concept of acceleration.

Paper airplanes are wonderful tools for illustrating many physics concepts, but the most fun is from making them and flying them.

We will be having an indoor competition for paper airplanes in two categories:

1) Distance/Displacement: Whose plane can go the furthest?

2) Duration: Whose plane can stay in the air the longest (the world record for this is 27.6 seconds).

The Rules: (check back here before you begin your project as the rules below may be changed)

• All work must be done on your own time, as an individual or as a team (you choose your team, maximum of four people).


• You may use only one 8.5 x 11 inch sheet of paper. The paper may be folded, cut or torn, but you are limited to that one sheet. Make sure you include identifying markings on your plane.


• You may use one paper clip and a small amount of adhesive tape (scotch tape or masking tape) in the construction of your plane.


• You must build two planes: one to fly and one to show how it was constructed.


• you may not use anything other than your hand/arm to lauch the plane.


• You will be allowed three attempts.


• Distance/Displacement will be measured as a direct line from the launch point to the point where the plane's motion stops, no matter which direction the plane traveled in its journey.


• Duration will be timed with a stopwatch.

The deadline will be announced (and published here) shortly. For extra credit, construct your best paper airplane and write a brief (two to four pages, with diagrams) report on one physics concept that can be explained and demonstrated using a paper airplane (not including acceleration). Be prepared to demonstrate this to your class. Prepare a summary handout or activity guide along with your presentation. Be sure to cite any and all information sources used and please, please see me before you begin so we can be clear on what is expected. Please leave a comment below if you intend on doing this.

Hot Wheels Challenge

For our next major project, we will be examining the motion of an unpowered wheeled object (one made by Mattel). Our research question for this next investigation (& ongoing report) is given two similar Hot Wheels cars, how do we determine beyond a doubt which one is faster?

As we discussed in class, this will involve designing experiments, writing procedures, trying them out, rewriting them, trying them out again, and so on until we can accurately answer the question.

The second question, of course, is to come up with definite reasons WHY one is faster than the other.

As we investigate these questions, we will encounter many of the following physics concepts:

• Linear Motion


• Speed


• Velocity


• Acceleration


• Acceleration due to Gravity


• Friction


• Momentum


• Newton's 1st Law

You can use the links on the side of the blog to clarify your understanding of these concepts. Post any questions you have on the blog using the comments link at the bottom of this entry.



Extra Credit Questions - Due by start of class on Tuesday, November 20 (you must show all calculations for credit on question 3) or you can submit your answers as a response on this blog or via email (you should know the email address - you wrote it into your notebooks on the first day or two of class)
1 - What is the scale of a Hot Wheels car? Cite your source.
2 - Give one example of Scalar vs. Vector quantities that we have recently studied (hint: we've studied two topics that include this, althought we never used "scalar" or "vector" in class)
3 - A car is moving at a constant speed of 88 km/hr when a traffic light ahead traffic light changes to red. It takes 8.0 seconds for the car to slow down and stop at the traffic light:
.. a) What is the car's initial velocity?
.. b) What is the car's final velocity?
.. c) What is the car's acceleration?
.. d) How far away from the traffic light was the car when the light changed?

Speed vs. Velocity

Now we know how to make a graph, and maybe how to read it.

What's Next? Speed and Velocity - Are they the same thing?

If not, can you come up with a good example of how they are different?

In class, we associated linear motion with speed - is velocity related to linear motion?

Linear Motion: Average, Constant & Instantaneous Speed

Questions from Class - Based on your understanding of Speed:

What does speed measure?

What is the Formula for Average Speed?

What is the difference between average speed and instantaneous speed?

An airplane is flying at a constant (also called “uniform”) speed of 400 miles an hour for three hours.
1. What is the plane’s instantaneous speed two hours into the flight?
2. How far will the plane travel in three hours?
3. How far will the plane travel in thirty minutes?

A runner runs at a constant speed of 7 mph in a marathon (note: a marathon is a race of 26.2 miles).
1. How far would she run in:
- One hour?
- Two hours?
- Three hours?
- Three hours, 30 minutes?
2. What was her time at the 14 mile mark?
3. What was her average speed during the race?

Extra Credit: One point each, answers must be precise to the second. Print this out and give it to Mr. Barkan with your answers (show ALL work or no credit!) no later than 2:30 pm on Thursday, November 1st for credit.
i. How long (in hours, minutes and seconds) did it take her to finish the marathon?
ii. What was her pace per mile? (i.e., How long, in minutes and seconds, did it take her to run a mile at that pace)?
iii. If she ran the marathon at a constant speed of 10 minutes per mile, how long would it take her to finish?
iv. What are the current NYC Marathon Men’s and Women’s Course Records?
v. What pace (constant speed) would a Male and a Female runner have to maintain to beat the current NYC Marathon Course Records?
vi. What will the winning times be for the first male and female finishers at the NYC Marathon on Sunday, November 4th, 2007?

Linear Motion

The rules governing how things move along a line are known (formally) as One Dimensional Kinematics and are part of the branch of physics commonly referred to as Newtonian mechanics.

Our first formal investigation into the world of Newtonian mechanics saw a bowling ball being hurled down 120 feet of hallway.

Our investigation of this linear motion (motion in a line) began with timing how long it took the ball to pass by eight marked points, each 15 feet long.

We will use this investigation to determine how to measure and predict the "simple" motion of an object moving in a straight line.

Our first task will be to determine the speed of the ball.
Those students who have taken the time to read this will know that while we can try to figure out the ball's speed every 15 feet mathematically, it will prove far simpler to graph the data and interpret the graph to answer the question of what happened to the ball's speed as it moved down the hallway.

Grand Scale

How big is big? Take a peek at this video which demonstrates the scale of the planets and stars, starting with the planet Mercury and concluding with Red Supergiant star VV Cephei A, the biggest known thing in the universe.

Why 9th grade physics?

(!) Show this to your parents (!)

An article in Tuesday's NY Times Science Times, "When Science Suddenly Mattered, in Space and in Class", discussed the need for attention to learning science, and addressed when the different areas of science should be taught:

"the typical sequence of high school science instruction: biology, chemistry and then physics. It would make more sense in reverse, these people say, because the principles of physics underlie chemistry, which is crucial for an understanding of biology."

“biology is the most complicated of all subjects, and it is based on chemistry and physics.” And, he added, “there is nothing in chemistry, no fact of chemistry or process of chemistry that if you ask ‘Why does this happen?’ you don’t go back to physics.”

Notes on “The Disappearing Beaker” Investigation

What grade did you get?
Your first report has been marked with comments but has not been graded. The number of comments on your report does not necessarily affect your grade.

Please read carefully the comments we have taken the time to write down and make sure that your resubmitted report addresses all of them.


DUE DATE – In Class on MONDAY, SEPTEMBER 24, 2007

You must resubmit the report in class on Monday, with the original report attached at the back. We will again grade it and get it back to you as soon as possible.

Late Reports
Do not submit your report late. Late reports will lose 10 points (one letter grade) every day, including weekend days. DO NOT SUBMIT YOUR REPORT LATE!

Resubmission Policy
Each time a report is returned to you, you will have the opportunity to resubmit the report. You may resubmit a graded/commented report as many times as you want, however you must completely rewrite the report each time.

Resubmission Deadline
You will have up to a week after your report is returned to you to resubmit it. No resubmitted reports will be accepted after that week has passed.

Spelling & Grammar
No points will be taken off for spelling or grammar problems the first time you submit your report. However if you do not correct them when you resubmit your report, you will have points deducted.

Number your pages and make sure your name is on every page.

How Long Should The Report Be?
Longer is not always better. Be clear and accurate. Diagrams & drawings that help explain what you are describing are an important part of physics.

Writing Style
The purpose of the lab report is not to tell a story. Take “You” out of the introduction, materials list and procedures. It is acceptable to discuss your experiences in the observations section as you recall it and also to ask questions in the conclusions section.


Make Each Section Distinct:

• Introduction
• Materials
• Procedure
• Observations
• Discussion
• Conclusions

Your introduction or the summary of your investigation should not include the detailed list of steps (the procedure) that describes how to do the investigation was conducted.

The procedure should not include your observations.

Be sure your conclusions are not part of your observations, and it’s always nice to end your report with a mention of additional things you might want to try based on the results of this investigation.

Find a Friend
Reread your report before you submit it. Have someone in your group read it as well or ask Ms. Purpura or Mr. Barkan to look it over before the due date so you have a chance to redo your report if necessary. We will do this in class on Monday.

He ATE the candle?????

Yes indeed... In today's class observation exercise, Mr. Barkan and Ms. Purpura ate... a candle. The expensive tool used to make the "candle" was the hollow tube of a ball-point pen.

Physics Blog Bonus:
We are going to be looking at some interesting optical illusions.

Extra credit will be earned by the first person in each class to
construct and demonstrate one of these:

Class Roles, Safety Policy

Class Roles:

• STARTER: Group Marshall (the “nudge”), timekeeper
  
• GETTER: Only person to ask questions, get & return supplies
  
• RECORDER: Responsible for all members of group taking consistent and complete notes
  
• REPORTER: Spokesmodel for group, takes notes on how group worked together

If you are late to class or somehow miss a class, it is important that you seek out your group's recorder and get caught up on what you missed. This is YOUR responsibility. Absence from class is not a valid excuse for not handing in or participating in an assignment or project. One way to ensure that you do mot miss anything is to be sure you have ways to contact (e-mail, phone #'s) of members of your group or a member of the class that you can rely on.

Classroom/Lab Safety Policy
You will receive a handout on "Safety in the Physics Laboratory", a written lab policy, which we will discuss in class. You must review with your parent/guardian and retur, signed (by both of you).
Please share your comments, questions or concerns with us by leaving a comment or by writing to Mr. B or Ms. P using the e-mails we gave you in class.

Physics News Assignments:
A written assignment sheet and due dates will be provided shortly.

2007 Class Requirements

Welcome to Freshman Physics with Mr. Barkan and Ms Purpura

Required materials for this course:

"Quad-Ruled" composition book - this will be your science journal. You will probably need more than one of them. Remember to leave the first three full pages (front and back) blank for now.

Calculator (the one you have to get for your math class)

Pen AND pencil, every day

Here's an additional list of helpful things to have. Note that these are not mandatory, but good to have for completing assignments outside of class. They will be provided in class as needed.

• Metric ruler
• Protractor
• Compass
• A set of color pencils, pens or markers
• Double-sided tape for attaching handouts to science journal (stapling stuff into the journal is not recommended)

Bring your science journal to class every day. We will be checking them on a regular basis - keeping a current notebook in the format we require will be a part of your grade, so it's probably a good idea to bring it with you every day. On Tuesday we will guide you through how we want you to organize your journal to ensure your success in the class.

You will be able to see your current grade(s) on TeacherEase in a couple of weeks.

PhET: Labs on your Laptop

Physics Education Technology - Interactive Physics Simulations

Fun, interactive simulations of physical phenomena from the Physics Education Technology project at the University of Colorado.

This site has flash and Java-based simlulations for just about every aspect of Physics we've covered.

Archimedes' Earthly Leverage

Simple machines. Archimedes knew about them. He was particularly fond of the lever. If given a big enough lever and a place to stand, he claimed (in a letter to King Hiero of Syracuse), he could lift the earth. (BUT COULD HE REALLY?)

"Plutarch says, "Once wrote to King Hiero of Syracuse, whose kinsman and friend he was, that this force could be used to move any weight. Carried away by the power of argument, he added that, were there another earth, he would go there and lift our own planet from it."

King Hiero, who was absolutely astonished by the statement, asked him to prove it. In the harbor was a ship that had proved impossible to launch even by the combined efforts of all the men of Syracuse. Archimedes, who had been examining the properties of levers and pulleys, built a machine that allowed him the single-handedly move the ship from a distance away. "

Simple Machines include the lever, something as straightforward as a wedge, and the one we're currently toying with in class: the pulley.

Speaking of Levers, Here's this week's Lab:
http://www.pbs.org/wgbh/nova/teachers/activities/2405_sle1obel_01.html

Bonus: - Interactive Demo: Can you lever an obelisk?

a body in motion

We all know about momentum, and not necessarily from physics. An idea can have momentum as readily as any object. In the world of physics, momentum is simply mass in motion.

We represent momentum with the lower case "p" and define it with the formula p=mv.

Click for some detail on momentum along with some interactive exercises.