Class on 10/19/09

Today in class we discussed a couple of concepts.  The first concept we discussed was Newton's 2nd Law.  This law states that  a = Fnet/m.  This law is also stated as Fnet = ma.  In both of these cases m = mass and a = acceleration.  There are many ways to interpret this formula.  First of all, it is shown that mass is inversely proportional to to acceleration.  This can also be proved by showing that 1/a is proportional to m.  Also, in this formula is it shown that acceleration is directly proportional to Fnet.  All of these conclusion can be proved by breaking down the formula a = Fnet/m.

Examples:

1/a  (proportional to)  m    a  (proportional to)  Fnet  a  (proportional to)  1/m

The other concept we discussed was free - body diagrams.  We went over an exercise we completed in Minds on Physics, and discussed all possibilities with the problems given.  There were examples when we would be given a diagram, and we would have to say whether or not it was valid, and also examples when we would have to name forces given the description of an event and a valid diagram.  We then discussed free - body diagrams and what goes in them.

• They show forces that act on an object
• They only show forces (no velocity or acceleration vectors)
• They NEVER show Fnet
• All vectors start at a center point and move in the direction of the force in relation to the object
• All forces are resembled by vectors

In class, we also had time to work on our labs and have small discussion about the main ideas of the lab.  At the end we were given some time to work on homework, and put some finishing touches on our lab.

October 5, 2009

yesterday in class we did reassessment chapters 1 and 2, then we worked on our projects for ten minutes then we all presented out texting while driving projects.

Class 9/15/09

Today in class we took the fourth reassessment then we went over some housekeeping rules. After this we split up into our stopping distance lab groups and did activity 25 in our MOP books. We learned how to find the area of a graph with constant velocity. To find this you find the area of the rectangle by doing time multiplied by the velocity and then add the area of the triangle by doing half the time by the velocity. Then we graphed the the velocity's and areas. That was what we learned and did in class.

In class today...9/24/09

Erica accidentally posted this to the other class:

In class today, for our lab we measured the velocity of Ryan and Kyle while they were running. We placed different members of our class at different positions for 26 meters. When Kyle and Ryan passed a person, that person would record the time that it took for Ryan and Kyle to reach them. Kyle and Ryan ran in both the positive and negative direction. Once we collected all of the data we were able to make a position vs. time graph for both Ryan and Kyle. Once we graphed the position vs. time graph for each runner we created a best fit line and calculated the average velocity for Ryan and Kyle. We calculated two average velocities, one when they were running in the negative direction and one when they were running in the position direction. Because we were on a hill, the negative direction was downhill, and the positive direction was uphill.

Thursday, September 10

Today in class, we started off by taking reassessment 3. After that, we learned about acceleration. Acceleration is the time rate at which velocity changes. We looked at a velocity vs. time graph with a diagonal line with a positive slope.The slope of the graph was acceleration. The graph showed constant acceleration. We also went over the fact that if you take the are of the figure made from the line and the x axis, this figures out displacement, or change in x.
Next, we looked at the acceleration of a basketball using a motion sensor. First, we dropped the ball while the motion sensor was hanging above the board pointing down. We mad two graphs: position vs. time and velocity vs. time. We figured out the acceleration of the basketball, which was 9063 meters per second squared. Then, we threw the ball towards the motion sensor and made the two graphs. We also repeated this for the bounce of the ball.
After this, we split off into groups and did a lab involving stopping distance. We pushed a felt covered block through a photogate and took data: the velocity and the stopping distance. We measured the stopping distance by measureing the distance from the edge of the photogate to the front end of the block. We answered some questions on the lab sheet, one including knowing the difference between average velocity and instantaneous velocity.

The next blogger is Erika.

Class on Wednesday

Today in class we did Re-Assessment number 2 and got back Re-Assessment number 1 and we looked over it and asked questions we had about it. After that we finished up the photo finish follow up sheet and we corrected it and answered questions we had about it.

The next scribe is Tanner

Changing Velocity Model

Thursday in class, we discussed the grading system and how school originated, all the way back to "cave school".After our discussion, we set up a photo finish between the impact carts and the buggies. We then measured and plotted the velocity of the impact carts using the motion sensor.

The next blogger is Carter

Friday, August 28

In last friday's class we worked with motion sensors to locate positons of a moving person. the motion sensors send out a sound and once it hits something thats in its path it bounces back giving the position of that object. When we used the sensors they would be plugged into the computor and the computor would collect all the data using a position Vs. time graph. From there we would calcutate the constant velocity at which the person/object was moving.

chip capper

the next person has already been named but it was caroline

reviewing constant velocity

Today in class we got back together with our groups from the toy car assignment. We wrote down how you would make a graph, equation, and in your own words about the constant velocity of the car. The equation was x=0.45(m/s)t. The constant velocity is change in position over change in time. On a graph if the slope is constant it shows constant velocity. We talked about what things in life have constant velocity. Cornelius said Kangaroo's and we discussed how it is not constant. I said a car on cruise control has a constant velocity. Merritt said that everything in the room thats standing still has a constant velocity. In terms of it being on earth it is just standing still but the earth is turning, and moving around the sun so it does have a constant velocity. Then we did a Bogus worksheet. We had to define it and say why things were bogus. the rest was for homework.
The next blogger is.. Merritt

Graphing Motion

Today during class, we learned a lot about star trek, but most importantly, how to graph motion. We started with a star trek activity where we tried to record relevant information while Mr. Burk gave us a lecture. From that lecture, we figured out what the speed for the scenario was at a maximum impulse. We used a position versus time graph to graph the information we recorded to end the activity.

From this, we were able to move on to the buggy lab. We were split up into lab groups and were each given a meter stick, a buggy, and a stopwatch. For this sheet, we had to time how fast it took our buggy to go certain distances. Then, using what we learned from the previous activity, once we had multiple times, we each made a graph.

To end the class, we had a buggy race!! (red won!)

Kathryn
The next scribe will be Sloan Krakovsky.

Domino Rallies

Today in class, we discovered what photo gate timers were. They are pieces of digital technology that are shaped like arcs and connected to poles. These poles are connected to either a small weighted platform (secondary timer) or a larger thicker platform that actually records the time on a display. We then discussed what the timers can measure, what they can help measure, or how they measure. It turns out the timers measure time and not necessarily speed itself, however they can't always be used in the traditional way (to tell/take times). They only record time INTERVALS in a way that is somewhat similar to a stopwatch. The choice to either use a photo gate timer or a stopwatch needs to be made carefully. A stopwatch is used to record general time intervals, but a photo gate timer records time intervals with more precise accuracy.

To make a photo gate timer work, you choose one of the three settings (pulse, gate,
pendulum). Next, you activate one of the arcs by breaking this line of light between (one end of the arc and another end). This starts the timer, and to stop the timer, the other arc's line of light must be broken. When we got to the subject of dominoes, we brainstormed ideas for experiments/labs that would lead us to the discovery of something new. We eventually concluded on the question,"Does the spacing of dominoes affect the speed of a domino rally". We selected a set number of dominoes and spaced them using a certain length from back to front. Next, we set up the photo gate timers with one arc right behind the first domino, and the second directly over the last domino. We knocked the dominoes over, then recorded the time that appeared on the timer. We recorded data for all trials, then recorded a class table with all of our results.

After the class table was made, we discussed graphing. If you did not know, the dependent variable goes on the Y(vertical axis) and the independent variable goes on the X(horizontal axis). The dependent variable is the non constant (uncontrolled) variable, and the independent variable is the controlled variable. Always include labels, units, a title, and a line of correlation. Plot coordinates based on your data.

This is what took place in class today

The next scribe will be Kathryn

Ace Neely-Chandler (Cornelius Chandler)