Do Now

Do NowComplete the problems under Do Now on your Daily Organizer. Todays Agenda Todays Agenda Important dates & remindersMonthly News ProjectDue TODAYProgress Reports Homework due tomorrow Scheduled to come out on Friday Incredible Pizza TripMoney due TODAY! Auburn College Trip Money and permission slips due FRIDAY! Todays Agenda Work When a force causes an object to be displaced (move or change positions). Work requirement In order for a force to actually have done work on an object, there must be a displacement and the force must cause the displacement

Calculating work F is the applied forceD is the distance your object was displaced is the angle between your force and displacement

UNITS: Joules (J)W = FdcosPositive, Negative, and Zero WORK

Positive work: Force is in the same direction as the movement of the objectex. pushing a book across a table Negative work: Force is in the opposite direction as the movement of the objectex. Lowering a heavy weight to the floorZero work: Force is at a 90 degree angle to the movement of the objectex. Pulling a dogs leash up as it walks forward9Review problem A box is pushed 4 m across a table with an applied force of 3 N. How much work was done on the book?What is the angle between the force and displacement? Review problem A child is pulling on a rope to drag his backpack to school across the ice. He pulls upwards and rightwards with a force of 20 N at an angle of 35 degrees above the horizontal to drag his backpack a distance of 70 m to the right. Determine the work done on the backpack.Todays Agenda What is power?We know that work is when a force causes some displacement. Work has nothing to do with the amount of time it takes to move that object thoughYou can change positions very slow or very fast and you wouldnt know based on work by itself. Power is the rate that work happens.

Another power equationYou can rework the equation for power to get a new equation.

This shows us that something with a lot of power is both STRONG and FAST.

Group exampleDetermine the power required to do 300 J of work on an object in 6 seconds. Group example AnswerDetermine the power required to do 300 J of work on an object in 6 seconds. 50 WGroup example A new conveyor system at a local packaging plant uses an average force of 890 N to push large crates a distance of 12 meters in 22 seconds. Determine the power required of these motors. Group example Answer A new conveyor system at a local packaging plant uses an average force of 890 N to push large crates a distance of 12 meters in 22 seconds. Determine the power required of these motors. P = 485 WTag teamTo complete the following two problems, we are going to be playing Tag Team. One of you will start out by setting up the problem using the equation(s) and the other will work on solving the problem. Tag Team problem 1A 10 N force is required to move a 3.0 kilogram box at constant speed. How much work is done to move the object 8 meters?How much power is required to move the box those 8 meters in 2.0 seconds?Tag Team problem 2During a lab, Alex runs up the stairs, elevating his 75 kg body a vertical distance of 5 meters in a time of 2.5 seconds at a constant speed.Determine the work done by Alex in climbing the stair case.Determine the power generated by Alex.Multiple choice cardsThe following are a series of multiple choice questions. Use the provided cards to show your answer when time is called. Multiple choice Problem 1Power isThe amount of work done over a certain amount of timeThe amount of force done over a certain amount of timeThe amount of work done over a certain distanceThe amount of force done over a certain distance

Multiple choice PROBLEM 1 ANSWERPower isThe amount of work done over a certain amount of timeThe amount of force done over a certain amount of timeThe amount of work done over a certain distanceThe amount of force done over a certain distance

Multiple choice PROBLEM 2Jordan needs to lift up a box of tools. He uses 2000 J of work in 5 seconds. How much power did he use?400 J400 W10000 J10000 W

Multiple choice PROBLEM 2 AnswerJordan needs to lift up a box of tools. He uses 2000 J of work in 5 seconds. How much power did he use?400 J400 W10000 J10000 W

Multiple choice problem 3Which of the following is not a valid equation for power? P = W / tP = Fd / tP = Fv / tP = Fv Multiple choice problem 3 AnswerWhich of the following is not a valid equation for power? P = W / tP = Fd / tP = Fv / tP = Fv Multiple choice problem 4A 680-newton student runs up a flight of stairs in 11.4 seconds. The student takes 8.5 seconds to run up the same flight of stairs during a second trial. Compared to the first trial, the second trial requiresThe same work and more powerThe same work and less powerMore work and less powerLess work and more power

Multiple choice problem 4 AnswerA 680-newton student runs up a flight of stairs in 11.4 seconds. The student takes 8.5 seconds to run up the same flight of stairs during a second trial. Compared to the first trial, the second trial requiresThe same work and more powerThe same work and less powerMore work and less powerLess work and more power

Multiple choice Problem 5You apply a force of 100 N to an object causing it to move with a constant velocity of 3 m/s. What is the power you are generating? 33 W66 W100 W300 W

Multiple choice Problem 5 AnswerYou apply a force of 100 N to an object causing it to move with a constant velocity of 3 m/s. What is the power you are generating? 33 W66 W100 W300 W

Challenge questionThe human brain requires 0.02 kW of power to operate. If GA Power charges $0.05 per kilowatt hour, how much money would you be charged to use your brain for 10 learning days at school if each day is 8 hours long?

Challenge question The Taipei 101 in Taiwan is a 1667-foot tall, 101-story skyscraper. The skyscraper is the home of the worlds fastest elevator. The elevators transport visitors from the ground floor to the Observation Deck on the 89th floor at speeds up to 16.8 m/s. Determine the power delivered by the motor to lift the 10 passengers at this speed. The combined mass of the passengers and cabin is 1250 kg.Challenge question Answer The Taipei 101 in Taiwan is a 1667-foot tall, 101-story skyscraper. The skyscraper is the home of the worlds fastest elevator. The elevators transport visitors from the ground floor to the Observation Deck on the 89th floor at speeds up to 16.8 m/s. Determine the power delivered by the motor to lift the 10 passengers at this speed. The combined mass of the passengers and cabin is 1250 kg.2.06 x 105 WIndependent practice Complete the Independent Practice problems on the back of your Daily Organizer silently and independently. Todays Agenda Exit Ticket Exit tickets are my daily way of seeing whether or not you have understood the objectives we have gone over during class each day.They are NOT be graded for accuracy but WILL be graded for completion so make sure you always try each and every question.These exit tickets must be done silently and independently. If you violate this, you will lose your participation points for the day.