Physics with Mr. Pritts
Sunday, March 18, 2012
Class discussion question
Energy is always "conserved" in nature. The practice of turning your lights off and trying to use energy efficient appliances is really reducing energy consumption, not conserving it. As we start our unit on electricity, here's a question to answer. What three electrical appliances in your house/apartment use up the most energy and why did you pick those three?
Photo-finish
The photo-finish
In the Summer 2008 Olympics, American swimmer Michael Phelps had a record breaking performance in which he won 8 gold medals. His most dramatic victory was the 100m butterfly in which he had a come from behind victory to win a photo-finish by 0.01 seconds. No human can detect 1/100th of a second with the naked eye, which is why we use electronic timing in sporting events.
Here is a (slightly dramatic) video of the race. http://www.youtube.com/watch?v=wIAg9wcriro.
Phelps is on top. Cavic is on the bottom.
Official results from espn.com
Michael Phelps - 50.58s
Milorad Cavic - 50.59s
1/100th of a second doesn't seem like much, so here's how we can use physics to make it more concrete. Phelps finished a 100m race in 50.58 seconds, so he was moving at an average of 1.977m/s. So in 0.01 seconds, he moves 0.01s*1.977m/s = 0.0197m, which is just under 2cm. 2cm isn't a lot, but it's more concrete than a time that's quicker than a human can detect.
Your job is to find another close timed race and get the official results with a picture. Make an estimation of how much distance separated first and second place. Please post the results, the picture, and your estimation.
In class, we will break down our visual estimations with some mathematical estimations.
In the Summer 2008 Olympics, American swimmer Michael Phelps had a record breaking performance in which he won 8 gold medals. His most dramatic victory was the 100m butterfly in which he had a come from behind victory to win a photo-finish by 0.01 seconds. No human can detect 1/100th of a second with the naked eye, which is why we use electronic timing in sporting events.
Here is a (slightly dramatic) video of the race. http://www.youtube.com/watch?v=wIAg9wcriro.
Phelps is on top. Cavic is on the bottom.
Official results from espn.com
Michael Phelps - 50.58s
Milorad Cavic - 50.59s
1/100th of a second doesn't seem like much, so here's how we can use physics to make it more concrete. Phelps finished a 100m race in 50.58 seconds, so he was moving at an average of 1.977m/s. So in 0.01 seconds, he moves 0.01s*1.977m/s = 0.0197m, which is just under 2cm. 2cm isn't a lot, but it's more concrete than a time that's quicker than a human can detect.
Your job is to find another close timed race and get the official results with a picture. Make an estimation of how much distance separated first and second place. Please post the results, the picture, and your estimation.
In class, we will break down our visual estimations with some mathematical estimations.
Welcome to the Physics Class blog
Physicists,
Welcome to Mr. Pritts's physics blog! This blog is open to all the students taking physics and will be a forum for discussion and sharing of physics related topics. Physics is arguably the oldest science and studies the matter of the universe and how it moves and changes. Because physics is all around is, it is important to see the ways in which physics applies to everyday activities like walking down the street, driving in a car or the subway, turning on a light, etc. I encourage you to use this blog to engage physics and your classmates outside the classroom.
This is the place to share and utilize some of the many fantastic physics web resources on the internet. Please post links to helpful physics-related websites, ask questions, engage me and your classmates in discussion, and help bring physics outside the classroom. If you want to make a video explaining the physics of some activity, this is the place for that.
A couple ground rules for comments and postings.
1. This blog is a physics class blog. It is not Facebook, or Twitter, or anything like that. Keep your activity here on topic.
2. Be respectful. There is no tolerance for talking down to any of your classmates here.
Lets have a great year together.
Welcome to Mr. Pritts's physics blog! This blog is open to all the students taking physics and will be a forum for discussion and sharing of physics related topics. Physics is arguably the oldest science and studies the matter of the universe and how it moves and changes. Because physics is all around is, it is important to see the ways in which physics applies to everyday activities like walking down the street, driving in a car or the subway, turning on a light, etc. I encourage you to use this blog to engage physics and your classmates outside the classroom.
This is the place to share and utilize some of the many fantastic physics web resources on the internet. Please post links to helpful physics-related websites, ask questions, engage me and your classmates in discussion, and help bring physics outside the classroom. If you want to make a video explaining the physics of some activity, this is the place for that.
A couple ground rules for comments and postings.
1. This blog is a physics class blog. It is not Facebook, or Twitter, or anything like that. Keep your activity here on topic.
2. Be respectful. There is no tolerance for talking down to any of your classmates here.
Lets have a great year together.
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