Do I have to show my work?

 Yes. As we are finding out in class, this is one of the most important parts about solving these one-step equations in motion.  By writing down the equation and filling in the values and measurement units, one can think if the answer is logical. For instance, if you calculate distance but your answer comes out to be 5 m/s, then you know there is an issue with the set up of the equation. Distance would have units of m for meter or km for kilometer. 

Another reason for including units in your calculation is to make sure that the values do not need to be converted. In class we completed several examples where units needed to be changed in order to solve the problem. For simplicity, we know that there are 1,000 m in one kilometer and 3,600 s in one hour. This knowledge will convert most of the units in our motion equations.

Here is a problem from class today: 

If a car is traveling 100 km/h and comes to a stop in 3 min, what is the car's acceleration? (round to the nearest hundredth, m/s²)

 

First, check to make sure you know what the problem is asking you to solve.

Velocity (initial) V_i = 100 km/h
Velocity (final) V_f = 0 km/h
Time is = 3 min
Acceleration = ? Solving for acceleration km/h²or  m/s²

Converting time to seconds 

Converting km/h to m/s

Now that we have the correct units, it’s time to solve the problem using the correct equation.

Velocity (initial) Vi = 27.8 m/s
Velocity (final) Vf = 0 m/s
Time = 180 s
Acceleration = ? Solving for acceleration, m/s²

 

Using units lets us know that the problem was solved correctly. For acceleration, the problem was to have an outcome with the units m/s². If we were to solve the problem and a different set of units were to be produced, then we’d know there was an issue in solving the problem.

Update:

Homework:

F3 Homework: Elements of Motion due next science class
F4 Quiz - Motion on Friday!



Extra Credit

VocabTV directions - due Wednesday
YouTube Video blog comment directions - due Thursday

Acceleration is a change in velocity...

In yesterday's class and blog post I described how changes in velocity can be a lot of fun especially at amusement parks. We continued that theme today by examining some specific examples. A lot of the students in the class have ridden the Top Thrill Dragster at Cedar Point, Ohio. This roller coaster once held the fastest and tallest category.

We know the Top Thrill Dragster uses a catapult system to launch the train to 200 km/h in 4 seconds from being at a complete rest or 0 km/h. How fast does the Top Thrill accelerate?

Video is from YouTube.

With the information above we can calculate the acceleration of the train as it leaves the station and approaches the hill. Unlike conventional coasters, Top Thrill does not have a lift hill. We can calculate the acceleration of the train on the coaster using the following equation and method:

So the Top Thrill Dragster travels away from the station going 14 m/s faster per each second. That is a fast ride!

In class we also looked at the acceleration of jet aircraft as they start from a stop at the runway. For planes to takeoff, they must quickly accelerate down the runway to reach take off velocity. From the pilot's point of view, the acceleration is very apparent because of the increasing speed of the hash marks moving past the aircraft. We also looked at negative acceleration for planes landing. The video used in class included this KLM-747 takeoff and landing from a small island airport.

These videos are from YouTube.

Update:

Homework:

F2 Reading Activity (notes) due toda
F3 Homework: Elements of Motion due Monday


Extra Credit

VocabTV directions
YouTube Video blog comment directions

Velocity is fun!

One of the topics in today's class was the idea that "spinning rides" are a lot of fun because they affect us with changing velocities. The students and I talked about the feelings we get while being on attractions like the Musik Express and Kangaroo at Kennywood. We also compared these rides to sitting in the back seat of a car in a curve. That feeling of being pushed toward the outside of the curve in the road is part of changing velocities. As we discussed, a car, a ride, or a roller coaster may maintain its speed, but it's the velocity change that makes motion exciting and fun. 

Update:

Homework:

F2 Reading Activity (notes) due today or tomorrow
F3 Homework: Elements of Motion due Monday


Extra Credit

VocabTV directions
YouTube Video blog comment directions

How fast is that?

In class we are exploring the speed at which objects are moving. Speed is the distance an object goes in a certain amount of time. Usually speed has measurement units such as mph (mi/h), km/h, and m/s. Speed can be used to think about how fast you must go to reach your destination on time, or average speed. So if you were to drive from Pittsburgh to Erie, what average speed would you drive to reach Erie in 3 hours? Speed can also tell how fast an object is moving at that moment, also known as instantaneous speed. This is the type of speed is used by police officers to determine if a car is within the speed limit.

One fast example from class was the speed record for the TGV, ultra-high speed train. Operating in France, the TGV hit 574.8 km/h in the year 2007. How fast is 574.8 km/h?  We've been exploring how to convert units for comparison.

So the train was moving 160 m/s when it hit the record. That’s 160 meter sticks end-to-end being traveled in one second. That is a fast train! Is this record average or instantaneous speed?

This video is available from YouTube.

Updates

Homework: F2 Reading Activity "Motion" Chapter 2 is due tomorrow, 2/24/2011. Need help getting started? Here is the partially setup version of the reading activity.
Extra credit is available and directions can be seen from the class website.

Snow Day, Online Content Available, and Extra Credit

With today's unexpected day off, I figured I could do some updates on the website. I am uploading the notes, practice problems, and tutorials to the website. The latest assignments are available for download too (F2 Reading Activity and F3 Homework: Elements of Motion). For a complete list of graded assignments for Unit F, Newton's Laws, download the assignment sheet.

Extra Credit! - Choose only one!

  
Also available are two extra credit activities that will be available on Wednesday. First is the VocabTV activity where students design one PowerPoint slide for the classroom TV. All of the submitted PowerPoint slides will be displayed throughout the day. Animated slides are due to me by Wednesday (March 2, 2011) by email, flashdrive, or Edline submission. More information about VocabTV is available in the linked document (pdf).

Second is adding content to this blog. Students are encouraged to look online for a YouTube video that helps the class understand speed, acceleration, or velocity. The students are to post the video to the blog as a comment. All that students need to do is copy and paste the YouTube address into the "post a comment area." Students need to write 3-5 sentences about why their video is a good example of speed, acceleration, or velocity. Be sure students include their name to indicate who submitted the video. More information about the YouTube video and submitting content can be read in this linked document (pdf). All student names will be removed from content before videos and sentences are posted to the blog. This activity is due by Thursday, March 3, 2011.

Data Analysis

As we investigate motion on inclined planes, we wanted to show the relationships in the data. Using graphs the students determined the patterns between the boards and the angle of the inclined plane. The students described the motion of the ball as a change in "speed." The ball was going faster as a result of angle. The change in speed was defined as "acceleration." In most cases the ball accelerated in a non-linear fashion. The students pointed out that as the inclined plane became steeper, the ball was accelerating less. Thus the graphs showed a curve.

Updates and Assignments
Next, the students are going to explore motion in more depth. Using the physics formulas for speed and acceleration, we will look at how moving objects behave.  The latest assignment sheet is available for download. Also, the textbook reading activity, F2 Chapter 2 was assigned and is due for Wednesday, 2/23/11. Assignments are available from the website.

What does the data tell us?

"Is there a mathematical relationship between 'steepness' and the time it takes a ball to travel the length of an inclined plane?" 

As the students explore Newton's Laws through inclined planes, we have expressed the need to look carefully at data. The type and quality of numbers that are collected during an experiment will determine success. The questions we've raised today ranged from outliers to the appropriate number of trials. The teams will have to examine what makes a good data set and determine their confidence that the numbers are both accurate and precise.

Next Monday we will be exploring what the groups have uncovered so far about motion.  We will talk about the numbers they have collected and address any issues they have had. We will also begin to analyze the information to see what patterns are in the data set regarding motion and the inclined planes.

The unit test scores were very impressive. The average for the entire 8th grade was 87%. The scores for the unit assessment are available on Edline. Great work students!

Ramp It Up! with Netwon's Laws

In Ramp It Up! we are investigating Newton's principles of motion. Student teams in my different classes are independently investigating what happens to an object as it rolls down a ramp. We have stated "what will happen to the motion of the ball?" as our guiding question. The ball seems to travel down the ramp with less time with a higher angle. But that leads us to question the relationship between the "steepness" and the time the ball travels down the ramp. Is there a mathematical relationship between the two variables? Hopefully the classes will uncover some of the scientific principals behind the motion of objects.

End of the Unit & Assessing Progress

Over the past few days my classes have been retaking a quiz on balancing chemical equations. The idea that atoms can neither be created nor destroyed in chemistry is a powerful one. No chemical reaction will ever destroy an atom. Through balancing the chemical equations, we can show how this physical law is true. The chemical equation, showing a chemical reaction, indicates the amount of reactants and products. It also has a strong connection to mathematics. Just like an equation in algebra, the values on either end of  the equation must be the same. I have seen a lot of growth in the scores from the first Smart Response questions to the last quiz. Great work students!

Today was also the unit test. I am interested in seeing how everyone has progressed up to this final assessment. What have we learned about everyday chemicals and their impact on our lives? How do those nanoscopic atoms affect how a compound is made? Hopefully, everyone has gained an appreciation for chemicals and how we use them in our daily lives.

As we progress into the second part of the third nine-weeks, we begin a unit on Newton's Laws. To help explore these topics, the students will work on Ramp It Up (dealing with inclined planes) and  bridge engineering (part of the Pittsburgh Unit).

Science 8 Blog!

This is the new science 8 blog. I hope to maintain this blog as a place for students and parent to learn more about what we are doing in class. I will use this area to exhibit some of activities and information we are covering in class. By using the blogger website, I hope to make it easier for people to connect, reference and review information that is posted. Check back often as the blog grows!