3/11 Physics update and homework due 3/18

Hi folks,

Today we continued to explore the relationship between force, distance and work as we took a look at the lever.  We discussed the three classes of lever and then did a lab where we could clearly see the effect of the placement of the fulcrum on the effectiveness of the lever.

For homework this week please do the following questions.  I've included your data sets so you can see your numbers.

1. What happened to the effort force as the fulcrum got closer to the load? 

2. What happened to the effort force as the fulcrum got farther from the load? 

3. What happened to the load force as the fulcrum got closer to the load? 

4. How about when the fulcrum got farther from the load? 

5. If you wanted to lift an object that you couldn't lift by yourself, where would you put the fulcrum? Close to, or far from the load? 

6. What relationship does distance have to force in regards to the lever?

7.  Make a graph with "Distance from the Load" on the x axis (the horizontal one) and "Effort Force" on the y axis (the vertical one).  Please use graph paper for this.

8.  We've stated again and again that simple machines do not change how much energy must be used to do a job.  So, what happened in this lab where we can clearly see that work in usually is not equaling work out?  Are we breaking the law of conservation of energy?  Nope, that cannot be broken so what is going on?  Something is not being measured/taking into consideration in this lab.  What is it?  

EXTRA CREDIT OPPORTUNITY!!  Once you answer #7 and know what is not being measured, can you figure out a way to calculate, using numbers you've already measured, what is missing?

ALSO, we haven't done much work with conversion in class and it's a good idea to be familiar with it.  Remember that energy can change forms and science has a variety of different units for energy depending on which form it is in.  This worksheet is a way to spend some time getting to know the different forms of energy and how they relate to one another.

I've included the answers for you so you know if you are on the right track.

ANOTHER EXTRA CREDIT OPPORTUNITY!!!  Eat a meal, then figure out how many calories you just ate by using one of many different websites or apps. (Something to keep in mind here, food calories are really KCals so be sure to use the right conversion factor. If a burger is 800 calories that's really .8 kcals)  Now convert that to Joules.  Now convert that to how much gasoline that would be.  Last but not least, if the energy in your meal could be converted in order to move a car, how far would the car go?  (Feel free to use the internet to find the miles per gallon of any automobile you wish.  I'd recommend a fuel efficient car if you want to go anywhere.  :)   )