Hi folks,
Today we continued our investigation into energy and work. We have begun to take a look at simple machines and how they relate to the concept of work. We used pulleys to discover the inverse relationship between distance and force.
Most of today was spent reviewing problems and doing our pulley lab so there will be no recording this week.
For homework this week:
Read the pulley chapter in the book.
Also, answer the following questions.
1. With the pulleys, how did work out relate to work in?
2. What relationship did force have in regards to distance as you worked with the pulleys?
3. As you increased the number of pulleys, what effect did that have on the effort force? What effect did it have on the effort distance?
4. a. If you were lifting a load that required a force of 10N with one pulley, what effort force would be required?
b. Same question, but now you're using 2 pulleys?
c. How about 10 pulleys?
5. a. If you were lifting that load 1 meter, what would the work in distance be for one pulley?
b. 2 pulleys?
c. 10 pulleys?
Monday, January 30, 2017
Make up test for Physics
Hi folks,
It looks like we need a bit more work with some of these problems so I'm going to assign a take home quiz. Feel free to use your notes for this. It will be worth 20 points just like a normal quiz. Please use this to attempt to master these problems. They will certainly be back to haunt you on the final if not sooner.
Good Luck!
Jim Mueller
It looks like we need a bit more work with some of these problems so I'm going to assign a take home quiz. Feel free to use your notes for this. It will be worth 20 points just like a normal quiz. Please use this to attempt to master these problems. They will certainly be back to haunt you on the final if not sooner.
Good Luck!
Jim Mueller
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
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