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Warm-up Get out your Conservation of Mechanical Energy Labs.  Lets talk about the graph Warm-up Get out your Conservation of Mechanical Energy Labs.  Lets talk about the graph

Warm-up Get out your Conservation of Mechanical Energy Labs. Lets talk about the graph - PowerPoint Presentation

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Warm-up Get out your Conservation of Mechanical Energy Labs. Lets talk about the graph - PPT Presentation

Warmup Get out your Conservation of Mechanical Energy Labs Lets talk about the graph before you turn it in On your warmup sheet What is power Reminders WednesdayProgress Reports ThursdayParentTeacher Conference Night ID: 774154

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Warm-up Get out your Conservation of Mechanical Energy Labs. Lets talk about the graph before you turn it in. On your warm-up sheet: What is power? Reminders Wednesday-Progress Reports Thursday-Parent-Teacher Conference Night Friday- Unit 6 Test

Power

Power Power - the quantity that measures the rate at which work is done or energy is transformed. SI Unit is the watt, W .Watt is a joule per second.“Horsepower” = 746 watts. P = Power [W]W = Work [ J ]∆t = time interval [s] = average velocity [m/s]    

Mountain Roads What are the advantages of such a design? Assuming mechanical energy is conserved , the same amount of energy is needed to reach the top using both paths. Because the same amount of work must be done, the path with the longer distance takes more time and requires less power.

Light bulbs A light bulb is described as having 60 watts. What’s wrong with this statement? Light bulbs don’t have energy stored within them; energy is transferred to them in the form of electricity at a rate of 60 J/s. Decorative lights- 0.7 WOutdoor lights- 7 W A dim light- 40 WBright bulb- 500 W

Practice 1 Two horse pull a cart. Each exerts a force of 250.0 N at a speed of 2.0 m/s for 10.0 min. Calculate the power delivered by the horses. How much work is done by the two horses?

Practice 2 A 193 kg curtain needs to be raised 7.5 m, at constant speed, in as close to 5.0 s as possible. The power ratings for three motors are listed as 1.0 kW, 3.5 kW, and 5.5 kW. Which motor is best for the job?

Warm-up On your warm-up sheet: Make a list of variables. DO NOT COPY THE QUESTIONS! How long will it take a runner to do 1,000 J of work if his power is 125 W? Jessica moves a book with a force of 2 N. The book moves 1.5 m in the direction of the force. How much work has Jessica done?If it takes Jessica 2 s to move the book, calculate Jessica’s power .RemindersWednesday-Progress ReportsThursday-Parent-Teacher Conference NightFriday- Unit 6 Test