 Work – the product of force and the distance traveled  The unit of Work is a Joule (J)  Work= Force × distance W = F ● d Distance (m) Force (N) Work (joules)

 Pushing a Crate 10 feet? OR  Pushing a Crate 100 feet?

 During the ascent phase of a rep of the bench press, the lifter exerts an average vertical force of 1000 N against a barbell while the barbell moves 0.8 m upward. How much work did the lifter do to the barbell?  Force =  Distance =  Work = 1000 N 0.8 m (1000 N) × (0.8 m) = 800 joules

 Calculate the work needed to push a block with 4 newtons of force a distance of 10 meters.  Force =  Distance =  Work = 4 N 10 m (4 N) × (10 m) = 40 joules

 An automobile engine exerts a force of 500 newtons on a car to travel 4,000 meters. What is the amount of work done by the engine?  Force =  Distance =  Work = 500 N 4,000 m (500 N) × (4,000 m) = 2,000,000 joules

 Power – the rate of doing work  The Unit of Power is a Watt (W)  Power = Work time (in seconds)  P = W same as P = F d t t

 He-Man who can push a crate 100 feet in 1 second using 5 Newtons? OR  Skeletor, who can push a crate 100 feet in 45 seconds using 5 Newtons? 1 second 45 seconds

 How much power is necessary to do 50 joules of work in 5 seconds?  Work =  Time =  Power = 50 joules 5 s (50 J) ÷ (5 s) = 10 watt

 An electrical water heater raises the temperature of water by adding 8,000 joules of energy to the water in 40 seconds. What is the minimum power required by the water heater?  Work =  Time =  Power = 8,000 joules 40 s (8,000 J) ÷ (40 s) = 200 watt

 Jake, who weighs 680 newtons, climbs a 6 meter ladder in 8 seconds. What was Jake’s power?  Force =  Distance =  Work =  Time =  Power = 680 N 6 m (680N) × (6 m) = 4,080 joules 8 s (4,080 J) ÷ (8 s) = 510 watt

 You may listen to music  Work quietly, do NOT talk!  Turn it in when complete  Finish in class, homework if you do not finish in class.