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Work and Energy

Learn about mechanical energy, work equations, types of mechanical energy, and the application of simple machines in daily tasks. Explore the concept of work in various scenarios and understand the significance of mechanical energy in everyday life.

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Work and Energy

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  1. Work and Energy

  2. Not a type of energy: a) Chemical b) Electrical c) Mechanical d) Political

  3. Not a type of energy: a) Chemical b) Electrical c) Mechanical d) Political

  4. By definition, Mechanical Energy means “the energy required to:” • Boil water • Fix a car • Move an object • Heat a home

  5. By definition, Mechanical Energy means “the energy required to:” • Boil water • Fix a car • Move an object • Heat a home

  6. Two types of mechanical energy: • Nuclear and Electrical • Electrical and Kinetic • Kinetic and Gravitational • Thermal and Electrical

  7. Two types of mechanical energy: • Nuclear and Electrical • Electrical and Kinetic • Kinetic and Gravitational • Thermal and Electrical

  8. The General Equation for all Mechanical Work is: a) W = Fxd b) W = mgh c) W = ½ mv2 d) W = mg

  9. The General Equation for all Mechanical Work is: a) W = Fxd b) W = mgh c) W = ½ mv2 d) W = mg

  10. Work can be done by: • Boiling water • Raising a book onto a shelf • Accelerating a mass • All of the above

  11. Work can be done by: • Boiling water • Raising a book onto a shelf • Accelerating a mass • All of the above

  12. I can do work by: • dropping a book. • Holding a heavy bag of groceries • Skateboarding at a constant speed. • Doing push-ups

  13. I can do work by: • dropping a book. • Holding a heavy bag of groceries • Skateboarding at a constant speed. • Doing push-ups

  14. I can do work by: • Writing a letter • Jogging to school • Climbing stairs • Building a fort

  15. I can do work by: • Writing a letter • Jogging to school • Climbing stairs • Building a fort • All of the above (trick question!)

  16. The Earth does work when: • I lift a book on to a shelf • I am tobogganing down a hill • I drive my car • I skate along the canal

  17. The Earth does work when: • I lift a book on to a shelf • I am tobogganing down a hill • I drive my car • I skate along the canal

  18. A ramp has an IMA of 5. This means: • It takes a force of 5N to push a 1N weight up the ramp. • It takes a force of 1N to push a 5N weight up the ramp. • If it takes 5J of energy to lift an object without the ramp, it will only take 1J of energy using the ramp. • If it takes 1J of energy to lift an object without the ramp, it will take 5J of energy using the ramp.

  19. A ramp has an IMA of 5. This means: • It takes a force of 5N to push a 1N weight up the ramp. • It takes a force of 1N to push a 5N weight up the ramp. • If it takes 5J of energy to lift an object without the ramp, it will only take 1J of energy using the ramp. • If it takes 1J of energy to lift an object without the ramp, it will take 5J of energy using the ramp.

  20. A simple machine: • Allows us to do the same work with less energy. • Allows us to do the same work with more energy. • Allows us to do the same work with less force. • Allows us to do the same work with more force.

  21. A simple machine: • Allows us to do the same work with less energy. • Allows us to do the same work with more energy. • Allows us to do the same work with less force. • Allows us to do the same work with more force.

  22. A frictionless pulley system has an IMA of 5. Which is True: • To lift a mass up 5m, I need to pull 1m of rope • To lift a mass up 1m, I need to pull 5m of rope • To lift a 1N weight, I need a force of 5N. • None of the above

  23. A frictionless pulley system has an IMA of 5. Which is True: • To lift a mass up 5m, I need to pull 1m of rope • To lift a mass up 1m, I need to pull 5m of rope • To lift a 1N weight, I need a force of 5N. • None of the above

  24. A pulley system has friction. Which of the following is FALSE: • The AMA of the system is less than the IMA of the system. • The efficiency of the system is less than 100% • It will take more force to lift the weight using the pulley system than without the pulley system. • It will take more energy to lift the weight using the pulley system than without the pulley system

  25. A pulley system has friction. Which of the following is FALSE: • The AMA of the system is less than the IMA of the system. • The efficiency of the system is less than 100% • It will take more force to lift the weight using the pulley system than without the pulley system. • It will take more energy to lift the weight using the pulley system than without the pulley system

  26. To pull a nail out of a block of wood, you need a lever with a high MA because: • You need a lot of force to move a small mass. • The nail moves a greater distance than your hand does. • A small force from your hand will be converted into a larger force pulling the nail. • You want to pull the nail using less work.

  27. To pull a nail out of a block of wood, you need a lever with a high MA because: • You need a lot of force to move a small mass. • The nail moves a greater distance than your hand does. • A small force from your hand will be converted into a larger force pulling the nail. • You want to pull the nail using less work.

  28. This machine has an IMA less than 1.0: • Crowbar • Baseball bat • Ramp • Hole punch

  29. This machine has an IMA less than 1.0: • Crowbar • Baseball bat • Ramp • Hole punch

  30. Beaker tongs have an IMA of 1.0. The tongs are used because: • They allow us to grip the beaker without burning our fingers • They reduce the force on the beaker, making it less likely to break. • They increase the force on the beaker, making it less likely to slip. • They allow us to lift a heavy beaker with less force.

  31. Beaker tongs have an IMA of 1.0. The tongs are used because: • They allow us to grip the beaker without burning our fingers • They reduce the force on the beaker, making it less likely to break. • They increase the force on the beaker, making it less likely to slip. • They allow us to lift a heavy beaker with less force.

  32. A machine has an efficiency of 80%. This means: • The machine is frictionless • The AMA is less than the IMA • The IMA is less than the AMA • Applied force is more than the load force

  33. A machine has an efficiency of 80%. This means: • The machine is frictionless • The AMA is less than the IMA • The IMA is less than the AMA • Applied force is more than the load force

  34. A skateboarder is gliding down a hill. Halfway down the hill, the total energy of the skateboarder is: • Eg • Ek • Ek + Eg • mcΔT

  35. A skateboarder is gliding down a hill. Halfway down the hill, the total energy of the skateboarder is: • Eg • Ek • Ek + Eg • mcΔT

  36. A skateboarder sits at rest atop a ramp. The speed of the skateboarder halfway down the ramp is calculated. The LOC of energy says: • Ek = Eg’ • Ek + Eg = Ek’ + Eg’ • Ek = Eg’ + Ek’ • Eg = Eg’ + Ek’

  37. A skateboarder sits at rest atop a ramp. The speed of the skateboarder halfway down the ramp is calculated. The LOC of energy says: • Ek = Eg’ • Ek + Eg = Ek’ + Eg’ • Ek = Eg’ + Ek’ • Eg = Eg’ + Ek’

  38. A block of ice is heated to 50oC. The energy to do this is: • mcΔT • mlf • mcΔT + mLv • mcΔT + mLf + mcΔT

  39. A block of ice is heated to 50oC. The energy to do this is: • mcΔT • mlf • mcΔT + mLv • mcΔT + mLf + mcΔT

  40. A cup of molten (melted) lead is allowed to cool to room temperature. The heat lost by the lead is: • mcΔT • mlf • mcΔT - mLv • mcΔT - mLf + mcΔT

  41. A cup of molten (melted) lead is allowed to cool to room temperature. The heat lost by the lead is: • mcΔT • mlf • mcΔT - mLv • mcΔT - mLf + mcΔT

  42. Water is brought from room temperature to 200oC. The energy required to do this is: • mcΔT + mLf • mLf + mLv • mcΔT – mLf + mcΔT • mcΔT + mLv+ mcΔT

  43. Water is brought from room temperature to 200oC. The energy required to do this is: • mcΔT + mLf • mLf + mLv • mcΔT – mLf + mcΔT • mcΔT + mLv+ mcΔT

  44. It takes 400J of energy to bring a car from rest to 10km/h. How much energy does it take to bring the same car from rest to 50km/h? • 800J • 2000J • 4000J • 10000J

  45. It takes 400J of energy to bring a car from rest to 10km/h. How much energy does it take to bring the same car from rest to 50km/h? • 800J • 2000J • 4000J • 10000J

  46. It takes 100J to lift a weight a certain height. How much energy does it take to lift the same weight twice the height? • 100J • 200J • 300J • 400J

  47. It takes 100J to lift a weight a certain height. How much energy does it take to lift the same weight twice the height? • 100J • 200J • 300J • 400J

  48. Joe is twice the mass of Jill. They enter a race and finish at the same time. Which is true? • They burned the same amount of calories since they both did the same distance. • Joe burned twice as many calories as Jill • Jill burned twice as many calories as Joe • Joe burned four times as many calories as Jill

  49. Joe is twice the mass of Jill. They enter a race and finish at the same time. Which is true? • They burned the same amount of calories since they both did the same distance. • Joe burned twice as many calories as Jill • Jill burned twice as many calories as Joe • Joe burned four times as many calories as Jill

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