Chapter 8, Lesson 1, "What is Work?"



Drip the Metric System: Have each site select a student who will be the teacher today. Show the students a picture of a meterstick and have that student tell the others about it. Show a blow-up picture of the meterstick and have that student tell the others about it. Show the students a picture of a square meter and have the student tell the others about it. Show the students the picture of a cubic meter and have that student tell the others about it. Show the student a picture a cubic decimeter and of a liter and have the student relate that to the cubic meter. Show the students a milliliter and ask the student/teacher to relate that to a cubic centimeter and the liter. Show the students a gram and have them relate that to the milliliter.

Anticipatory Set:* Tell the students that a scientist would define work as work = Force x Distance. Show the students this picture and tell them that the force must be in the direction of the distance moved. If that is not the case no work is being done. With that in mind remind them of the pictures from yesterday and have them get out the sheet that they wrote on predicting whether work was happening. go through each with the formula on them. Is there work happening picture 1, picture 2, picture 3, picture 4, picture 5, picture 6, picture 7. Now for the tough one. Is work happening in this picture?

Teacher Input:* In the formula work equals force times distance we need to figure out what the units should be. Remember that a force is a push or pull upon an object resulting from the object's interaction with another object. Whenever there is an interaction between two objects, there is a force upon each of the objects. When the interaction ceases, the two objects no longer experience the force. Forces only exist as a result of an interaction. Do any of the students remember what the metric unit of force or weight is? Remind them of the Newton. Newtons can be measured with a spring scale. This spring scale does not really measure grams does anyone know why? One Newton is the amount of force required to give a 1-kg mass an acceleration of 1 m/s/s. When measuring work distance is usually measured in the standard metirc unit of distance. What is that? So we have Work = Newtons x Meters. Remember that Newtons come from Kg • m / s2 Instead of using all these units the scientific community created the term Joule to stand for all that.

So, given this girl pushing her bike, how much work is she doing? Which of these people is doing more work? Guy one. Guy two. Read the did you know and explain that if both mowers are the same mass They are doing the same work however, the boy is pushing in the direction he wants the mower to go. The tall man pushes with more downward force so not all the force is being exerted in th direction of the mower so he is exerting more force.

Splash the concept of heat:* Ask the students what temperature it is at their site? What does that mean? What does a thermometer actually measure? Heat always moves from warmer to cooler areas so where does it come from? Almost all heat can be tracked back to a nuclear reaction in our sun.

Guided Practice:* Students will take turns answering the questions for review on Page 208.

Independent Practice:* Students will read Lesson 1, What is Work, pages 206-207. Students will complete the worksheet, 08-01, What is Work?9

Check for Understanding:* Students will take the quiz, 08-01, What is Work?



30 minutes + 10-15 for Independent Practice (Could be longer if taken for homework).

Alaska Content Standards Addressed in this lesson: