Name: ______Class:______Date:______
Chapter 4 Section 1 Objectives:
- Students will be able to explain and properly use the key vocabulary in the chapter correctly: work, kinetic energy, joule, power, watt
- Students will be able to determine when work is being done on an object.
- Students will be able to calculate the amount of work done on objectsas force and distance vary.
SCIENCE INFORMATION LIST
You must keep a copy of this in your notebook with the documents that you have been given listed on it. All information should then be attached to this list in the order that you received and entered it onto this list. IT MUST BE HANDED IN ON THE DAY OF THE QUIZ
NEVER THROW YOUR CLASS MATERIAL INCLUDING HOMEWORK AWAY.
IF YOU ARE MISSING MATERIALS PRINT THEM FROM MY WEBSITE!
TOPICS: ______
Date received / Title of Material / Check box when material is completed and attachedDay 1: Read each statement and put true or false in the box marked pre-assessment in front of each statement.
Pre-assessment(True or False) / Statement
1. Anytime a force is applied to an object, work is being done.
2. Power, work, and force are the same thing as one another.
3. “More power’ means doing work faster.
4. Playing baseball is work.
5. It is the same amount of work to rock climb up the face of a mountain to the top as it is to walk up a winding path to the top.
6. In order to figure out how much work is done, you must know how much force is applied and the distance the object moves.
7. It takes the same amount of power to sand a piece of wood by hand as it does to use an electric sander.
Homework: Provide 6 examples of objects in motion, the direction of the force, the direction of the motion, and if work is being done.
WORK OR NO WORK ?
Example / Direction of force / Direction of motion / Doing Work?HOMEWORK: Calculating Work
As you sit and read this worksheet, are you doing work? You might say, “Yes, of course.” But are you doing work in the scientific sense? Scientists use the word work to describe a very specific concept. In physics, work is a force applied over a distance.
EQUATION: Work = Force X distance
W = F x d
The SI unit for work is the newton-meter (N•m), also known as a joule ( J). You can calculate the amount of work accomplished with the equation above. Let’s see how it’s done!
SAMPLE PROBLEM: How much work is done on a 16 N sack of potatoes when
you lift the sack 1.5 m? W = F x d
W = 16 N x 1.5 m
W = 24 J
Work It Out! Based on what you know about work, answer the following questions. Be sure to show your work.
1. A deflated hot-air balloon weighs a total of 8000 N. Filled with hot air the balloon rises to a height of 1000 m. How much work is accomplished by the hot air?
2. A rope is thrown over a beam, and one end is tied to a 300 N bundle of lumber. You pull the free end of the rope 2 m to lift the lumber off the ground. How much work have you done?
3. You use 75 N of force to push a box 3 m across the floor, how much work has been done?
4. A car’s brakes exert an average stopping force of 5000 N over a distance of 22 m.
How much work did the brakes do?
Chapter 4 Section 1
Name: ______Class:______Date:______
Calculating Power
Work is closely related to the concept of power. Power is a measure of how much work is done in a certain time or the rate at which work is done or energy transferred. The faster work is done, the more power is produced.
Power = Work / time
P =W/t
The unit for power is the watt (W). One watt (W) is equal to 1 J of work done for 1 second. Remember to show your work.
Chapter 4 Section 1
Name: ______Class:______Date:______
SAMPLE PROBLEM: A small motor can do 4500 J of work in 25 seconds, what is its power?
P = W/t
P = 4500 J / 25 s
P = 180 W
Chapter 4 Section 1
Name: ______Class:______Date:______
Work It Out! Based on what you know about work & power, answer the following questions. Be sure to show your work.
1. What is the power output for a light bulb that uses 1000 J of energy in 50 seconds?
2. If you ride your bike for 60000 seconds and do 360000 J of work, how much power did it take to ride your bike?
3. Over 100 seconds, a car’s brakes exert an average stopping force of 5000 N over a distance of 22 m.How much power did the brakes have to exert? (You will have to calculate work first!)
Chapter 4 Section 1
Name: ______Class:______Date:______
ADD THIS TO YOUR PACKET AND SAVE UNTIL THE CHAPTER TEST HAS BEEN COMPLETED!
Chapter 4 Section 1 Work and Power Post-Assessment
1. Day 4: Now that you have read the sectionread each statement and put true or false in the box marked post-assessment in front of each statement.
Post-assessment(True or False) / Statement
1. Anytime a force is applied to an object, work is being done.
2. Power, work, and force are the same thing as one another.
3. “More power’ means doing work faster.
4. Playing baseball is work.
5. It is the same amount of work to rock climb up the face of a mountain to the top as it is to walk up a winding path to the top.
6. In order to figure out how much work is done, you must know how much force is applied and the distance the object moves.
7. It takes the same amount of power output to sand a piece of wood by hand as it does to use an electric sander.
2. For each of the statements that are false, write the question number & provide a corrected statement below:
______
______
______
______
______
______
3. Compare your answers to your pre-assessment answers – how did you do?
“Mini-quiz” review
For your “mini-quiz” on this section you must be able to:
1. Explain and properly use the key vocabulary in the chapter correctly:
work
kinetic energy
joule
power
watt
- Determine when work is being done on an object.
- Calculate the amount of work done on objectsas force and distance vary using the formula W = F x d.
- Calculate the power it takes to perform work using the formula P = W/t.
Chapter 4 Section 1