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Do Now

Do Now. Complete the problems under Do Now on your Daily Organizer. Turn in Mid Year College Ready Reset papers. Today’s Agenda . Today’s Agenda . Important dates & reminders. Mid Year College Ready reset papers should be in the bin Report Cards

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Do Now

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  1. Do Now • Complete the problems under Do Now on your Daily Organizer. • Turn in Mid Year College Ready Reset papers

  2. Today’s Agenda

  3. Today’s Agenda

  4. Important dates & reminders • Mid Year College Ready reset papers should be in the bin • Report Cards • Scheduled to come out Thursday of next week. • No School Next Friday! • MLK Day Volunteering

  5. Today’s Agenda

  6. When a force causes an object to be displaced (move or change positions). Work

  7. 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

  8. Calculating work W = Fdcosθ • F is the applied force • D is the distance your object was displaced • Θis the angle between your force and displacement • UNITS: Joules (J)

  9. Positivework: 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 floor • Zero work: Force is at a 90 degree angle to the movement of the objectex. Pulling a dog’s leash up as it walks forward Positive, Negative, and ZeroWORK

  10. Review problem • A box is pushed 4m 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?

  11. 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.

  12. Today’s Agenda

  13. 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 though • You can change positions very slow or very fast and you wouldn’t know based on work by itself. • Power is the rate that work happens.

  14. Another power equation • You 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.

  15. Group example • Determine the power required to do 300 J of work on an object in 6 seconds.

  16. Group example Answer • Determine the power required to do 300 J of work on an object in 6 seconds. • 50 W

  17. Group 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.

  18. 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 W

  19. To 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

  20. Tag Team problem 1 • A 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?

  21. Tag Team problem 2 • During a lab, Kenneth runs up the stairs, elevating his 75 kg body a vertical distance of 5meters in a time of 2.5 seconds at a constant speed. • Determine the work done by Kenneth in climbing the stair case. • Determine the power generated by Kenneth.

  22. The following are a series of multiple choice questions. Use the provided cards to show your answer when time is called. Multiple choice cards

  23. Multiple choice Problem 1 • Poweris • The amount of work done over a certain amount of time • The amount of force done over a certain amount of time • The amount of work done over a certain distance • The amount of force done over a certain distance

  24. Multiple choice PROBLEM 1 ANSWER • Poweris • The amount of work done over a certain amount of time • The amount of force done over a certain amount of time • The amount of work done over a certain distance • The amount of force done over a certain distance

  25. Multiple choice PROBLEM 2 • Jordan needs to lift up a box of tools. He uses 2000 J of work in 5 seconds. How much power did he use? • 400 J • 400 W • 10000 J • 10000 W

  26. Multiple choice PROBLEM 2 Answer • Jordan needs to lift up a box of tools. He uses 2000 J of work in 5 seconds. How much power did he use? • 400 J • 400 W • 10000 J • 10000 W

  27. Multiple choice problem 3 • Which of the following is not a valid equation for power? • P = W / Δt • P = Fd/ Δt • P = Fv / Δt • P = Fv

  28. Multiple choice problem 3 Answer • Which of the following is not a valid equation for power? • P = W / Δt • P = Fd/ Δt • P = Fv / Δt • P = Fv

  29. Multiple choice problem 4 • A 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 requires • The same work and more power • The same work and less power • More work and less power • Less work and more power

  30. Multiple choice problem 4 Answer • A 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 requires • The same work and more power • The same work and less power • More work and less power • Less work and more power

  31. Multiple choice Problem 5 • You 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 W • 66 W • 100 W • 300 W

  32. Multiple choice Problem 5 Answer • You 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 W • 66 W • 100 W • 300 W

  33. Complete the Independent Practice problems on the back of your Daily Organizer silently and independently. Independent practice

  34. Today’s Agenda

  35. 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.

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