POWER Mrs. Anna Ward James Martin MS

DO NOW!!! 1. Alex used a force of 60 N to lift a heavy box over his head. If he moved it a distance of 1 meter, what was the force he used? 2. Sarah pushed a box across the classroom using 30 N of force and completed 240 J of work. How far did the box move? 3. Karla pushed Shikim down the hallway for 20 meters before he got away. She completed 100 Joules of work. How much force did she use?

Announcements Notebook check today The Quarter Final for Forces and Motion is next Friday Power Lab Monday. You must complete Homework Sheet to participate.

Agenda Review Power Practice Power Problems Independent Practice Fun Forces Foldable Fact & Function Finder

Reminder: Power Power is the rate at which work is done. Power = Work * /Time * (force x distance) The unit of power is the watt. 5

Power Problem #1 Ana does 60 Joules of Work in 20 seconds. What is her power?

Power Problem #2 Brandon does 400 Joules of work in 60 minutes? What is his power?

Power Problem #3 Tyana uses 50 Watts of power in 10 seconds. What is her work?

Power Problem #4 Dakenya uses 10 J or work and produces 470 Watts of work. How long did she work?

Independent Practice Sheets Use Power = work/time Remember, work is force x distance

Fun Forces Foldable Fact & Function Finder You are going to create a 6 page foldable with the following terms: Speed, Velocity, Acceleration, Force, Work, & Power On each page, you will include the following: Definition Formula Magic Triangle Unit of Measurement Hints are on board; please take good care of my copies

Check for Understanding 1.Two physics students, Ben and Bonnie, are in the weightlifting room. Bonnie lifts the 50 kg barbell over her head (approximately.60 m) 10 times in one minute; Ben lifts the 50 kg barbell the same distance over his head 10 times in 10 seconds. Which student does the most work? Which student delivers the most power? Explain your answers. 12

EXPLANATION Ben and Bonnie do the same amount of work; they apply the same force to lift the same barbell the same distance above their heads. Yet, Ben is the most powerful since he does the same work in less time. Power and time are inversely proportional. 13

2. How much power will it take to move a 10 kg mass at an acceleration of 2 m/s/s a distance of 10 meters in 5 seconds? This problem requires you to use the formulas for force, work, and power all in the correct order. Force=Mass x Acceleration Work=Force x Distance Power = Work/Time 14

2. How much power will it take to move a 10 kg mass at an acceleration of 2 m/s/s a distance of 10 meters in 5 seconds? This problem requires you to use the formulas for force, work, and power all in the correct order. Force=Mass x Acceleration Force=10 x 2 Force=20 N Work=Force x Distance Work = 20 x 10 Work = 200 Joules Power = Work/Time Power = 200/5 Power = 40 watts 15

EXIT TICKET How much power will it take to move a 20 kg mass at an acceleration of 3 m/s/s a distance of 10 meters in 5 seconds? This problem requires you to use the formulas for force, work, and power all in the correct order. Force=Mass x Acceleration Work=Force x Distance Power = Work/Time 16