# Use www.physicsclassroom.com

use this worksheet:
http://www.physicsclassroom.com/getattachment/curriculum/circles/circle.pdf
Test on this

## Videos:

http://www.learnapphysics.com/apphysicsb/work_and_energy.php
This unit is based on the idea that:
KE = 1/2 mv2
PE = mgh
W = Fd
KE = PE = W
1/2 mv2 = mgh= Fd
1 hp (horsepower) = 746 W
On the problem that says 'below the water’s surface, what is the total distance between the diving board and the diver’s stopping point underwater?" Just answer with the distant dropped to the water not the "total" distance.

Lab 1

Lab 2

Lab 3

## Discussion

re: 5 Work and Energy

nchsdowdyk Jan 21, 2010 7:04 am
The first thing you need to do is go to page 169 in your physics book and flip through that chapter and write down ALL the formulas in the yellow boxes. They are the only way you are going to get through this packet. Any time you see J(joules) it is a type of energy so you will be looking for something like PE(potential energy) or KE(kinetic energy). be sure to go ask Mrs. Duncan any time you have a question. She helps out a lot with the understanding how to use the formulas.

MarleeDW Jan 21, 2010 7:12 am
-Use Formulas in Ch. 5 but be sure that you understand the concept before. Some problems do not need the whole formula, parts cancel out and are not needed. But some problems need all parts of the formula.
-Draw the diagrams. It helps visualize the action and understand how to work the problem.
-List all givens, then look for a formula that fits. In some problems the mass does not matter and is not needed.
-Almost all of the problems center around the formula: KEi + PEi = KEf + PEf (KE = 1/2 mv^2 and PE = mgh)
-One Watt = 1J / Second
-Work = Force x Distance
-In the chapter, you have to remember how to find force net and work with gravity. (like the work we did before we started rotation).
-The Lab is simple, Ask Mrs. Duncan on the file to open because you have to mess around with it a little. The Lab Cart is found by the goggles and is big and red with a metal plunger sticking out the end with a spring in it. The probes are found on the shelf of boxes. The Box is labeled. And you will need and adapter.
Have Fun :)
Marlee Williams

cas4555 Feb 8, 2010 7:07 am
-Be sure to read over Chapter 5 and understand all the formulas before starting your packet.
-It's also beneficial if you write down the formulas throughout the chapter before starting also.
-One Watt-1J/Second
-Work=(Force x Distance)
-If you draw the diagrams it will help you visualize the action and understand how to work the problem better.
Alex Stuart

qib56 Feb 8, 2010 7:20 am
The lab is very easy and all the things you will need are on the shelf in the back. You will need to get the nail for the lab car out of the drawer on the island in the front of the room. and if you really don't know what I’m talking about just ask me. you use the formula KE=1/2m(v squared) and also net work is equal to change in kinetic energy.
Quinton B.

CSpears Mar 1, 2010 7:09 am
For this chapter and work, you will need all of chapter 5. Each formula is useful to your work. You need to read and understand the difference of kinetic and potential energy. You can also set kinetic equal to potential when answering a problem. (Hint: if the m for mass is on both sides in each expression, you can cancel each m out. Therefore, you may work problems with the mass included in the formula when a mass is not given, as long as they may cancel.) Make sure you look at each individual problem, and the diagram it is given. Draw the diagrams with all forces acting on the object to help guide you through each problem. Think about what you are given and how to use it to work the problem. For the lab, use a force folder on the lab pro and set the cart by a hard surface for it to push off of. The nail you need is in the long drawer in the front of the room. All the information you need to answer the lab is formulas worked out. Also, there is some that are descriptions. Use the information you have and the knowledge of all the work to complete each one. Good Luck! CSpears

RachelET Mar 1, 2010 2:29 pm
The rotation was tricky. What really helped me though was reading the chapter completely from end to end. I used every formula so it will probably be best to write each one down ad you go through the chapter. In one problem I had I used KE in the place of mechanical energy. Also DRAW diagrams they really do help because they help you to better understand what you are looking for and how to get it. KE can also be set to equal PE. Net force can be set to equal the change in kinetic energy. You will also need to pull out your notes from the beginning on this year when we studied forces and refresh yourself on those ideas. When a question ask for the answer to be in J it means you will use and formula that has energy in it because J is a type of energy. Sometime the formula isn't going to be right there and you will have to manipulate different formulas and set them equal to each other and then solve to equal what you are looking for. Also be sure to watch for careless errors because they are really easy to make.
Good luck,
Rachel T

andreashaycumberland Mar 3, 2010 7:10 am
The main formula I used was PEi + KEi=PEf + KEf so you need to know that one.
You may often have to revert back to the regular physics formulas on the board, and sometimes combine those with the new work and energy formulas with this chapter and for almost every one you have to draw a diagram to see what is happening.
Careless errors are extremely easy to make so make sure to watch out for that.
Also reading the chapter beforehand will help a lot.

nchshadenj Mar 26, 2010 7:06 am
If you're like me drawing a diagram will help visualize the problem. Make sure that your triangles are drawn correctly with the given angles in the correct positions. On the lab with the spring car, make sure that you switch the Pressure Sensor to 50N.