9/14/11
Commencing Countdown Engines On
Tomorrow is test day for all blocks. We reviewed for all blocks between yesterday and today, literally going page by page through the book to point out relevant things to know. You have all of your homework and labs in your hands. A review sheet is online, as are the worked out solutions to the problems and the PowerPoint lecture. So, you have a mess of tools and experiences to help you tomorrow. Remember that you'll get the formulas and remember to study your Ball Toss lab for the short answer that's going to concentrate on that investigation. I will be in before school tomorrow if you have any final questions, so stop in if you need help. Good Luck!
9/13/11
And More Free Fall
B and C Blocks conducted the Picket Fence Free Fall lab and got nice results. Demonstrated that acceleration due to gravity is constant, graphs of position-time, velocity-time and acceleration-time showed predicted patterns and that the measured value for "g" was pretty durn close to the actual value.
E Block reviewed their lab and homework problems for free fall before launching into a review for Thursday's exam. That's how things usually work - I'll go through the text pointing out what to know, and what you can slack off on, but it's on your shoulders to get any additional help you need before test time. That goes for all the blocks - are you listening B, C and E? Tomorrow, you'll get to work on a lab that will let you more fully work with free fall motion and give you a lot of practice interpreting and doing quantitative analysis of graphs. That will also serve as a good review for the test - remember, the write-up won't be due until Friday.
F Block ran a lab that analyzed the motion of a ball in free fall and spent a good portion of the lab block interpreting the graphs of the ball's motion. Make sure you are very clear about what each graph says about the motion and what information you can get from each graph. Consider well how the ball's motion and the patterns of the graphs document what we talked about in class.
Exam review tomorrow for B, C and E Blocks, so come with questions. Remember the online resources available to you and make good use of them for test preparation. This will not bail you out of a jam:
E Block reviewed their lab and homework problems for free fall before launching into a review for Thursday's exam. That's how things usually work - I'll go through the text pointing out what to know, and what you can slack off on, but it's on your shoulders to get any additional help you need before test time. That goes for all the blocks - are you listening B, C and E? Tomorrow, you'll get to work on a lab that will let you more fully work with free fall motion and give you a lot of practice interpreting and doing quantitative analysis of graphs. That will also serve as a good review for the test - remember, the write-up won't be due until Friday.
F Block ran a lab that analyzed the motion of a ball in free fall and spent a good portion of the lab block interpreting the graphs of the ball's motion. Make sure you are very clear about what each graph says about the motion and what information you can get from each graph. Consider well how the ball's motion and the patterns of the graphs document what we talked about in class.
Exam review tomorrow for B, C and E Blocks, so come with questions. Remember the online resources available to you and make good use of them for test preparation. This will not bail you out of a jam:
9/12/11
Free Fall
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.
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.
9/9/11
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.
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