Power Contents: Definition of Power Whiteboards Jambalaya Whiteboards

Power - The rate at which work is done TOC Power = Work/Time P = W/  t P = Power W - Work done  t - Time to do work A person does 145 J of work in 20.0 s. What is power output? P = W/  t = (145 J)/(20.0 s) = 7.25 J/s = 7.25 Watts = 7.25 W 1 horsepower = Watts, 1 kW = 1000 Watts

Power - The rate at which work is done TOC power = work/time = (Fd)/t = F(d/t) = Fv F = Force to move something v = Velocity it is moving P = Fv My 30. HP van could go 25 m/s top speed. What was the force resisting its motion? 1 horsepower = Watts, 1 kW = 1000 Watts power = (30 HP)(745.7 Watt/HP) = 22,371 W P = Fv 22,371 W = F(25 m/s), F = 890 N

Whiteboards: Power 11 | 2 | 3 | 4 | TOC

288 W W P = W/  t = (613 J)/(2.13 s) = 288 W Joe Mama does 613 J of work in 2.13 seconds. What is his power output?

5.28 s W P = W/  t,  t = W/P = (671 J)/(127 W) = 5.28 s Ima Wonder can put out 127 W of power. What time will it take her to do 671 J of work?

67,000 J W P = (1.5 HP)(745.7 W/HP) t = 60 s P = W/  t, W = Pt = ( W)(60 s) = J What work does a 1.5 HP motor do in 1 minute?

230 W W P = Fv = (43 N)(5.3 m/s) = W = 230 W Bob N. Frappels slides a box with 43 N of force at a constant speed of 5.3 m/s. What is his power output?

2.83 m/s W P = Fv v = P/F = (430 W)/(152 N) = 2.83 m/s Frieda People can put out 430 W of power. With what speed can she push a car if it takes 152 N to make it move at a constant velocity?

Power all mixed up Formulas: F = mg (Lifting) F =  mg (Dragging) F = ma (Accelerating) P = W/t (Power) P = Fv (Power) W = Fd (Work) v = d/t (Velocity) a =  v/t (Acceleration) Things we can know P - Power (in W) W - Work (in J) F - Force (in N) d - distance (in m) t - time (in s)  - coefficient of friction m - mass (in kg) v - Velocity (in m/s) a - acceleration (in m/s/s) It’s a Jambalaya!

Formulas: F = mg (Lifting) F =  mg (Dragging) P = W/t (Power) W = Fd (Work) P - Power (in W) W - Work (in J) F - Force (in N) d - distance (in m) t - time (in s)  - coefficient of friction m - mass (in kg) Sample 1 - A 1.2 HP winch can lift a 2350 kg LandRover up 14.5 m into a tree in what time?

Formulas: F = mg (Lifting) F =  mg (Dragging) P = W/t (Power) W = Fd (Work) P - Power (in W) W - Work (in J) F - Force (in N) d - distance (in m) t - time (in s)  - coefficient of friction m - mass (in kg) Sample 2 - Gumi Baere drags a 45.1 kg box that has a coefficient of friction between it and the floor of.34 a distance of 16 m in 11.7 seconds. What is her power output?

Whiteboards: Power Jambalaya 11 | 2 | 3 | 4234 TOC

11700 W F = mg = (560 kg)(9.8 N/kg) = 5488 N W = Fd = (5488 N)(3.2 m) = J P = W/t = ( J)/(1.5 s) = W What must be the power rating of a motor if it is to lift a 560 kg elevator up 3.2 m in 1.5 seconds? W

406 kg P = (.75 HP)(745.7 W/HP) = W P = W/t, W = Pt = ( W)(37 s) = J W = Fd, F = W/d = ( J)/(5.2 m) = N F = mg, m = F/g = ( N)/(9.8 N/kg) = 406 kg A.75 HP winch can lift a car 5.2 m in 37 seconds. What must be the mass of the car? 1 HP = W W

.22 W P = 2500 W P = W/t, W = Pt = (2500 W)(93 s) = J W = Fd, F = W/d = ( J)/(340 m) = N F =  mg,  = F/(mg) = (683.8 N)/ ( (312 kg)(9.8 N/kg) ) =.22 Red Elk leads a dog team that can put out 2.5 kW of power. They skid a 312 kg sled a distance of 340 m in 93 seconds. What must be the coefficient of friction?

2500 m P = (150 HP)(745.7 W/HP) = W F =  mg = (.78)(350 kg)(9.8 N/kg) = N P = W/t, W = Pt = ( W)(60 s) = J W = Fd, d = W/F = ( J)/( N) = 2508 m A 150 HP tractor can drag a 350 kg load how far in a minute if the coefficient of friction between the load and the ground is HP = W W