Hi folks,
Sorry, looks like I forget to attach the book. Here it is.
Wednesday, January 25, 2017
Tuesday, January 24, 2017
Recording of 1/23 Physics class - Work and "Punt the football" problem
Sorry about that last email. I sent the wrong recording. Here's the one for yesterday's class.
Monday, January 23, 2017
1/23 Physics class and homework due 1/30
Hi folks,
Last week we did a nice conceptual overview of what energy is and this week we got a bit more into the nitty gritty and mathematics behind energy. We introduced the concept that energy is the ability to do work and that work is equal to force times distance. To make that more concrete, we went outside and pushed my car again. This time, however, we measured the amount of force it took to move the car and measured how much time it took to move it. Using those measurements we calculated the energy it took for us to move the car and we found how many Watts and how much horsepower we used.
In my opinion the text that we're using goes into too little detail on energy. I'm including my Energy eBook to help supplement the text
Homework due next is to
Read the Defining Energy chapter in the eBook
In the Conceptual Physics text book do Plug and Chug Pg 120 #'s 1 and 3
And Think and Solve # 2, 4
I've included the answers for the problems below.
Plug and Chug
1. 20 x 3.5 = 70J
3. First find work from question #2.
500N x 2.2m = 1100J
Then take 1100 J/2 = 550W
Think and Solve
2. Twice the power would be 1/2 the time. So the answer is 5 s.
4. So the car starts with 40,000,000 J. If the car is 25% fuel efficient that means that only 25% of that goes to making the car move so only 10,000,000 of the energy is used. So now, plug n chug.
10,000,000 = 1000 x D
10,000 m = D Or 10 Km
Last week we did a nice conceptual overview of what energy is and this week we got a bit more into the nitty gritty and mathematics behind energy. We introduced the concept that energy is the ability to do work and that work is equal to force times distance. To make that more concrete, we went outside and pushed my car again. This time, however, we measured the amount of force it took to move the car and measured how much time it took to move it. Using those measurements we calculated the energy it took for us to move the car and we found how many Watts and how much horsepower we used.
In my opinion the text that we're using goes into too little detail on energy. I'm including my Energy eBook to help supplement the text
Homework due next is to
Read the Defining Energy chapter in the eBook
In the Conceptual Physics text book do Plug and Chug Pg 120 #'s 1 and 3
And Think and Solve # 2, 4
I've included the answers for the problems below.
Plug and Chug
1. 20 x 3.5 = 70J
3. First find work from question #2.
500N x 2.2m = 1100J
Then take 1100 J/2 = 550W
Think and Solve
2. Twice the power would be 1/2 the time. So the answer is 5 s.
4. So the car starts with 40,000,000 J. If the car is 25% fuel efficient that means that only 25% of that goes to making the car move so only 10,000,000 of the energy is used. So now, plug n chug.
10,000,000 = 1000 x D
10,000 m = D Or 10 Km
Tuesday, January 17, 2017
Monday, January 16, 2017
1/16 Physics update and homework due 1/23
Hi folks
We have finished our study of Newton's Laws and mechanics and have started our energy block today. We discussed how we perceive energy using our energy "antennae", our ears, eyes and skin. We also discussed how energy is like a phantom. It's invisible until it interacts with matter, it changes forms and it can neither be created nor destroyed.
For homework this week:
Study the "quiz" we did today in class. I've included a copy. Next week I will give another quiz that won't be the same as this one, but it will use the same concepts. Don't forget that to figure out acceleration you must use the time that the object is acceleration ONLY! So for today's quiz, you would only use the time that the fellow was flung in the slingshot. Not the entire time he was in the air.
Read chapter 8 pages 103- 119. (This will give you a brief overview of what we will be spending a lot of time on over the next few weeks. The book doesn't go into nearly the detail I think we need to spend on this topic.)
Do Review Questions 1 - 13 on page 119
We have finished our study of Newton's Laws and mechanics and have started our energy block today. We discussed how we perceive energy using our energy "antennae", our ears, eyes and skin. We also discussed how energy is like a phantom. It's invisible until it interacts with matter, it changes forms and it can neither be created nor destroyed.
For homework this week:
Study the "quiz" we did today in class. I've included a copy. Next week I will give another quiz that won't be the same as this one, but it will use the same concepts. Don't forget that to figure out acceleration you must use the time that the object is acceleration ONLY! So for today's quiz, you would only use the time that the fellow was flung in the slingshot. Not the entire time he was in the air.
Read chapter 8 pages 103- 119. (This will give you a brief overview of what we will be spending a lot of time on over the next few weeks. The book doesn't go into nearly the detail I think we need to spend on this topic.)
Do Review Questions 1 - 13 on page 119
Monday, January 9, 2017
1/9 Physics class and homework due 1/16
Hi folks,
Today we used just about every concept we've learned this year and applied our knowledge to the game of Angry Birds. We discovered the impulse, velocity, momentum and more of the different objects in the Angry Birds world. It was a very difficult challenge and folks really did a great job attacking the problems.
I've included the questions below in case you want to take a look at them. Here's a great write up of a fellow who did the same kind of a thing we did today. It's pretty interesting if you want to take a look. By the way, he calculates the slingshot to be 5 meters tall!
No recording this week since most of class was taken up by the activity.
Homework this week is a scavenger hunt. I want you all to find two examples of all the concepts written below.
Rules:
They must all be different.
They must all be photos taken with a camera (not images from the internet).
They can be things that you just come across or you can set up situations that exemplify the concept.
Write a sentence for each one indicating why that photo is an example.
Videos are allowed if you wish.
You can print out the photos to hand in or you can email them to me.
1. Newton's First Law
2. Newton's Second Law
3. Newton's Third Law
4. Momentum
5. Impulse
6. Acceleration
7. Inertia
Angry Birds Analysis
Some assumptions for you:
The time it takes the rubber band to hurl a bird is .05 sec. (This is the time of a pitch.)
The mass of the Red Bird is 6kg (the same as an eagle)
Gravity is normal 9.8 m/s2
Do # 8 first!!!!
1. What is the maximum horizontal velocity of an Angry Bird?
2. What is the maximum vertical velocity of the Angry Bird?
3. What is the maximum resulting velocity of the Bird?
4. Are all birds the same mass? How do you know?
5. What is the force of the rubber band?
6. What is the mass of a rock (be sure to describe what rock you're measuring)?
7. What is the impulse on the angry bird when it's fired.
8. What is the height of the sling shot?
9. Does the Blue Bird conserve momentum when it splits? How do you know?
10. What's the momentum of the Red bird?
11. Using Angry Birds give me one example of the following:
a) Newton's First Law
b) Newton's Second Law
c) Newton's Third Law
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