Today was dominated by a study of free fall with B, C and F Blocks engaging in a discussion of free-fall motion and E Block working on an activity to experimentally determine the value for acceleration due to gravity. That lab shows quite nicely that can be measured quite simply (as long as you have a photogate) and you'll use another method on Wednesday when you conduct a more extensive investigation on the free fall motion of a ball tossed in the air.
B, C and F Blocks tramped over familiar ground in their study of free fall, since the basic rules and formulas of kinematics apply equally to vertical and horizontal motion. As long as the only force producing significant acceleration on an object is gravity, the motion is easy to describe and predict. You know the acceleration will be -9.81 m/s2 and you know that at the highest point of the rise the velocity of the object will be 0 m/s. If the object is dropped from a height (already at it's highest point), the initial velocity is 0 m/s. Remember this when making your information list to solve problems. The book won't remind you in the problem's write-up, so you'll have to remember that on your own. You know that an object on the rise (with + velocity and - acceleration) will slow down and falling object (with - velocity and - acceleration) will speed up. Tomorrow, B and C Blocks will conduct an activity on acceleration due gravity and F Block will analyze the motion of a ball tossed into the air to determine if all this blah, blah, blah about free fall is really to be believed.
9/12/11
9/9/11
West Nile Virus
As you all know, we got the word that there mosquitoes in the area that tested positive for West Nile Virus. For more information:
Here's the cycle of infection:
Here's the culprit:
And here's the ad for the upcoming Universal Pictures film starring Keanu Reeves:
...ok... that last part was a lie...
Here's the cycle of infection:
Here's the culprit:
And here's the ad for the upcoming Universal Pictures film starring Keanu Reeves:
...ok... that last part was a lie...
Phinally Phriday!
And, phinally, the sun has peeked out. I will take this as a good omen...
Today was kinematics for B, C and F Blocks, which nicely capped off our stepwise investigation of the descriptors of motion (displacement, velocity, acceleration). Kinematics asks and answers questions about an object's motion, but what it does not address is the cause of the motion or the factors promoting a change in the motion. That's dynamics, and we'll catch that very soon. The homework problems are designed to give you practice in working with these formulas and, I strongly urge folk to really give them a try before looking up answers. Write down all your information and identify which variable each piece represents. Choose a formula to start working with that uses that information, or could be used to get you another piece of information with what you already have provided. Plug your variables into the formula and be very mindful of signs. Evaluate your answer logically and with common sense - does it seem right or not... Create a good problem-solving strategy now, because we are going to be doing this until June...
E Block discussed their Ball Toss lab and evaluated their results in light of our previous work on kinematics. The tossed ball is an example of an object in free-fall (if we assume friction is negligible, which our results said wasn't a bad assumption) and that was the topic of today's lecture. Free-fall motion is motion where the only force acting on the object is gravity. Anything tossed into the air or dropped from a height, without any additional propulsion supplied, is a candidate for free-fall. We spent time explaining the patterns of motion associated with free fall (lose velocity as rises, gains velocity as falls) in terms of our knowledge of the interplay between acceleration and velocity and added a few items to our mental tool box (acceleration due to gravity is constant and at the top of a rise and object's velocity is 0 m/s) to help set up and solve problems. On Monday, you will do an activity to demonstrate free-fall motion and establish experimentally a value for acceleration due to gravity.
Have a great weekend!
Today was kinematics for B, C and F Blocks, which nicely capped off our stepwise investigation of the descriptors of motion (displacement, velocity, acceleration). Kinematics asks and answers questions about an object's motion, but what it does not address is the cause of the motion or the factors promoting a change in the motion. That's dynamics, and we'll catch that very soon. The homework problems are designed to give you practice in working with these formulas and, I strongly urge folk to really give them a try before looking up answers. Write down all your information and identify which variable each piece represents. Choose a formula to start working with that uses that information, or could be used to get you another piece of information with what you already have provided. Plug your variables into the formula and be very mindful of signs. Evaluate your answer logically and with common sense - does it seem right or not... Create a good problem-solving strategy now, because we are going to be doing this until June...
E Block discussed their Ball Toss lab and evaluated their results in light of our previous work on kinematics. The tossed ball is an example of an object in free-fall (if we assume friction is negligible, which our results said wasn't a bad assumption) and that was the topic of today's lecture. Free-fall motion is motion where the only force acting on the object is gravity. Anything tossed into the air or dropped from a height, without any additional propulsion supplied, is a candidate for free-fall. We spent time explaining the patterns of motion associated with free fall (lose velocity as rises, gains velocity as falls) in terms of our knowledge of the interplay between acceleration and velocity and added a few items to our mental tool box (acceleration due to gravity is constant and at the top of a rise and object's velocity is 0 m/s) to help set up and solve problems. On Monday, you will do an activity to demonstrate free-fall motion and establish experimentally a value for acceleration due to gravity.
Have a great weekend!
9/8/11
Acceleration
We added the last descriptor of motion - acceleration - for C and F Blocks today. Keep in mind that acceleration is not just a change of velocity, it is the rate of velocity change and can involve both the speed of the motion and the direction. And be very mindful of the meaning of signs when evaluating accelerated motion. Acceleration and velocity can have the same sign, which means the speed increases, or opposite signs that indicate the speed decreases. We went over the situations where you have zero velocity but do have acceleration (like a ball at the top of it's rise) or where you have velocity but zero acceleration (object continues to move at constant velocity). We'll go over your homework problems tomorrow and then put all these descriptors together into what are called the kinematics formulas, which are powerful tools for analyzing the motion of objects.
F Block reached kinematics land today and, after an overview of the topic and relevant formulas, were given time for practice. It is easy to trip up with these - you get signs wrong, overlook implicit information, etc. - and, since we'll use them heavily, getting started on the right foot is important. We'll review these tomorrow before launching into a discussion of free fall and how to apply the kinematics formulas to objects in free fall.
B Block got to play with basketballs today to analyze their motion as they were tossed into the air. Position/time, velocity/time and acceleration/time graphs were generated and folks were able to put what we've been talking about in lecture to practice analyzing these graphs. It was to be expected that the position/time graph was curved because the motion had acceleration. It was to be expected that the velocity/time graph was linear because the acceleration was constant. That was reinforced by the acceleration/time graph, since it was basically a straight horizontal like right around -10 m/s2 (accepted value for acceleration due to gravity, on average, is -9.81 m/s2). Tomorrow, we'll discuss the lab and then head into our discussion of kinematics.
F Block reached kinematics land today and, after an overview of the topic and relevant formulas, were given time for practice. It is easy to trip up with these - you get signs wrong, overlook implicit information, etc. - and, since we'll use them heavily, getting started on the right foot is important. We'll review these tomorrow before launching into a discussion of free fall and how to apply the kinematics formulas to objects in free fall.
B Block got to play with basketballs today to analyze their motion as they were tossed into the air. Position/time, velocity/time and acceleration/time graphs were generated and folks were able to put what we've been talking about in lecture to practice analyzing these graphs. It was to be expected that the position/time graph was curved because the motion had acceleration. It was to be expected that the velocity/time graph was linear because the acceleration was constant. That was reinforced by the acceleration/time graph, since it was basically a straight horizontal like right around -10 m/s2 (accepted value for acceleration due to gravity, on average, is -9.81 m/s2). Tomorrow, we'll discuss the lab and then head into our discussion of kinematics.
9/7/11
Not a Happy Rain
Wow, is today dreary... luckily, we're studying motion which is FUN FUN FUN!!!
Ok, enough of that. B and E Blocks entered into a discussion of accelerated motion. Acceleration, the rate of change of velocity, can occur either through a change of speed or direction. We'll concentrate on the speed change for now, but remember the direction piece when we hit circular motion. We took time to look at acceleration conceptually, graphically and with equations and began to creep into a full kinematics discussion that we'll hit tomorrow for E Block and on Friday for B Block. Tomorrow, for B Block, is a lab that will let you examine the position-time and velocity-time graphs we've discussed and you will use them to interpret the motion of a ball in free fall - our next topic of study.
C Block conducted their Ball Toss lab and got very good results. The software provides position-time, velocity-time and acceleration-time graphs for a single piece of motion, so the movement of the ball through the air could be visualized and analyzed in a variety of ways. Consider the shape of each graph and make sure you explain them in your lab conclusions. Why do I expect the velocity/time graph to be nicely linear, for example... we'll go over the lab tomorrow before diving into a deeper study of acceleration. We'll hit the special circumstance of acceleration due to gravity a little later in the chapter.
F Block began their discussion of motion with an introduction to frame of reference and a few basic descriptors of motion. We took special care to distinguish the vector quantities (displacement and velocity) from the scalar ones (distance and speed) and make sure that, for tonight's homework, you include direction with your answers if the value is a vector. Tomorrow, we'll add another descriptor of motion - acceleration and then use all three on Friday to examine how we can use math to describe and make predictions about motion through the use of the kinematics formulas.
Maybe it will have stopped raining by then...
Ok, enough of that. B and E Blocks entered into a discussion of accelerated motion. Acceleration, the rate of change of velocity, can occur either through a change of speed or direction. We'll concentrate on the speed change for now, but remember the direction piece when we hit circular motion. We took time to look at acceleration conceptually, graphically and with equations and began to creep into a full kinematics discussion that we'll hit tomorrow for E Block and on Friday for B Block. Tomorrow, for B Block, is a lab that will let you examine the position-time and velocity-time graphs we've discussed and you will use them to interpret the motion of a ball in free fall - our next topic of study.
C Block conducted their Ball Toss lab and got very good results. The software provides position-time, velocity-time and acceleration-time graphs for a single piece of motion, so the movement of the ball through the air could be visualized and analyzed in a variety of ways. Consider the shape of each graph and make sure you explain them in your lab conclusions. Why do I expect the velocity/time graph to be nicely linear, for example... we'll go over the lab tomorrow before diving into a deeper study of acceleration. We'll hit the special circumstance of acceleration due to gravity a little later in the chapter.
F Block began their discussion of motion with an introduction to frame of reference and a few basic descriptors of motion. We took special care to distinguish the vector quantities (displacement and velocity) from the scalar ones (distance and speed) and make sure that, for tonight's homework, you include direction with your answers if the value is a vector. Tomorrow, we'll add another descriptor of motion - acceleration and then use all three on Friday to examine how we can use math to describe and make predictions about motion through the use of the kinematics formulas.
Maybe it will have stopped raining by then...
9/6/11
Motion!
B, C and E Blocks began their study of motion today with an overview of distance/displacement and speed/velocity. We will dig into the difference between scalar and vector quantities in more detail in the next chapter, but hopefully everyone got the basic idea that vectors require a statement of direction, whereas scalars only report magnitude. We also looked at the importance of a frame of reference for evaluating motion and started quantifying motion changes graphically and with the velocity formula. Tomorrow, C Block will conduct a lab investigation that will take a very graphical approach to the study of motion, using a motion detector to track a ball tossed into the air. B and E Blocks will move on to a discussion of acceleration and the major kinematics formulas.
F Block reviewed last week's material on the scientific method and metric system, then launched into the area of accuracy/precision. Accuracy problems are usually our fault somehow, but precision limitations stem from the physical design of the measuring tool. To correctly report the precision of a measurement, rely on significant figures. This is especially important with using several measurements in a calculation. In the case of ambiguous trailing zeroes, fall back on scientific notation. Truthfully, it's more efficient to report all values that way since it can make estimated calculations easier, but SI prefixes work well, also. Tomorrow - we begin our study of motion!
...and yes, this image is relevant to motion, so don't mock me...
F Block reviewed last week's material on the scientific method and metric system, then launched into the area of accuracy/precision. Accuracy problems are usually our fault somehow, but precision limitations stem from the physical design of the measuring tool. To correctly report the precision of a measurement, rely on significant figures. This is especially important with using several measurements in a calculation. In the case of ambiguous trailing zeroes, fall back on scientific notation. Truthfully, it's more efficient to report all values that way since it can make estimated calculations easier, but SI prefixes work well, also. Tomorrow - we begin our study of motion!
...and yes, this image is relevant to motion, so don't mock me...
9/5/11
Happy Birthday Freddie!
Freddie Mercury, lead singer of Queen would have been 65 today. The man had a 4-octave range (if you don't know why that's impressive, ask Mrs. Laflamme) and really entertained his audience in an age when Auto-Tuning and lip-synching were unheard of. The guys who do the Google doodles crafted a tribute and it's a hoot... BTW - did you know that Queen's guitarist, Brian May, has a Ph.D in Astrophysics...
9/4/11
9/1/11
And, We're Done
Short week due to the impending holiday, and what's better for a short week than a nice fire drill. C Block lost some time due to that, but we made it work. B and C blocks spent time discussing the concepts of accuracy and precision and why precision (though we sometimes don't give it it's fair due) is a vital part of reporting measurements. Through the use of significant figures and scientific notation, the precision of values can be made clear to everyone reading them, which is critical for science, medicine, engineering... On Tuesday, we start in on one-dimensional motion!
E Block had their lab period and conducted an introductory investigation to familiarize themselves with the Vernier probeware system. Between the sensors/probes and the data analysis features, this system allows for highly quantitative labs to be performed, which is the name of the game in physics. Also, the various sensors make possible a good number of measurements that more classical apparatus do not easily permit. We'll go over the lab on Tuesday and then hightail it into our study of kinematics. Remember to have both yesterday's assignment and the lab write-up ready to go on Tuesday.
F Block reviewed yesterday's lab and began a discussion of the metric system, dimensional analysis and the scope of physics. We'll round out Chapter 1 on Tuesday and find ourselves in our study of motion on Wednesday. Just a head's up - looking over the lab sheets, I noticed a lot of people didn't follow the proper procedure for writing the lab synopsis. I don't care if you do it in paragraph form or in a list, but ALL components should be there. Since this is the first one, I gave the people who did it correctly an extra point and those who did not still got full credit. Next time, though, expect a reduction in grade.
E Block had their lab period and conducted an introductory investigation to familiarize themselves with the Vernier probeware system. Between the sensors/probes and the data analysis features, this system allows for highly quantitative labs to be performed, which is the name of the game in physics. Also, the various sensors make possible a good number of measurements that more classical apparatus do not easily permit. We'll go over the lab on Tuesday and then hightail it into our study of kinematics. Remember to have both yesterday's assignment and the lab write-up ready to go on Tuesday.
F Block reviewed yesterday's lab and began a discussion of the metric system, dimensional analysis and the scope of physics. We'll round out Chapter 1 on Tuesday and find ourselves in our study of motion on Wednesday. Just a head's up - looking over the lab sheets, I noticed a lot of people didn't follow the proper procedure for writing the lab synopsis. I don't care if you do it in paragraph form or in a list, but ALL components should be there. Since this is the first one, I gave the people who did it correctly an extra point and those who did not still got full credit. Next time, though, expect a reduction in grade.
8/31/11
For Real, This Time
Yesterday was housekeeping, today was real work. B, C and E Blocks reviewed the scientific method and the basics of the metric system and checked the homework problems for metric conversions. As I said in class, the method you choose to perform unit conversions is up to you, as long as you do it correctly. You will find yourself often having to convert units (metric mostly, but some non-SI units, as well), so hammer that skill down now. Time was also taken to discuss the importance of models in physics and why their use is critical for analyzing complex systems. We will often make assumptions about a system that reduce it to a model and, surprisingly, still get respectable predictions of real-world events. Tomorrow (Tuesday for E Block), we tackle accuracy and precision, the use of scientific notation and significant figures and the value of checking answers for dimensional consistency.
F Block conducted an introductory lab investigation to get them used to working with the Vernier probeware system. Equal increments of pennies were weighed and graphed to explore how Vernier presents real-time data and how the program performs mathematical data analysis. We modified the experiment a little by having groups test both pre-1982 pennies and post-1982 pennies and comparing the weights. Remember to follow the instructions for writing a lab synopsis and answer all questions/perform all calculations required in the lab handout. E Block will perform this lab tomorrow and F Block will take up today's lecture material in class.
F Block conducted an introductory lab investigation to get them used to working with the Vernier probeware system. Equal increments of pennies were weighed and graphed to explore how Vernier presents real-time data and how the program performs mathematical data analysis. We modified the experiment a little by having groups test both pre-1982 pennies and post-1982 pennies and comparing the weights. Remember to follow the instructions for writing a lab synopsis and answer all questions/perform all calculations required in the lab handout. E Block will perform this lab tomorrow and F Block will take up today's lecture material in class.
8/28/11
11-12 is On!
Starting the new year is always a bother for both teachers and students, but hey... can't do anything about it so buck up and just get it done. This week is very short, but that doesn't mean we're going to be slacking. We'll be attacking Chapter 1, which introduces folks to the identity of physics and some of the fundamental skills you'll need throughout the year. Take time this week and weekend to make sure you have a good calculator to use - you WILL need it and the faster you get used to using it, the happier you will be. As for lab, we'll be working through an activity that will allow people to learn the Vernier system and get a feel for how the lab program will be conducted this year. And weigh pennies... Come on, you know playing with pennies is fun. Just admit it.
After this introductory chapter, we'll be moving directly into a study of motion. Distance/displacement, speed/velocity and acceleration are going to be the big players and there will be a set of formulas that you'll have to tackle to analyze the motion of objects. Get familiar with them - they are going to be your buddies for a good long, LONG, time in the course.
After this introductory chapter, we'll be moving directly into a study of motion. Distance/displacement, speed/velocity and acceleration are going to be the big players and there will be a set of formulas that you'll have to tackle to analyze the motion of objects. Get familiar with them - they are going to be your buddies for a good long, LONG, time in the course.
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