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How Can we Analyze the Total Energy in a System?

How Can we Analyze the Total Energy in a System?. By Laura Zinszer 2011 Columbia Public Schools & Physics First. All Energy is measured in a unit called a Joule . This unit is used. with all types of energy. It is abbreviated with a J.

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How Can we Analyze the Total Energy in a System?

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  1. How Can we Analyze the Total Energy in a System? By Laura Zinszer 2011 Columbia Public Schools & Physics First

  2. All Energy is measured in a unit called a Joule. This unit is used with all types of energy. It is abbreviated with a J.

  3. To understand total energy in a system, we must calculate both the potential energy and the kinetic energy.

  4. We will then add the Eg and Ek together.

  5. The formula for Total Energy becomes… • TE = Eg + Ek

  6. Let’s start with Gravitational Potential Energy (Eg)

  7. Gravitational Potential Energy (Eg) To determine the Eg use the formula… Eg = m * g * h Where m = mass g = 9.8 h = height

  8. For example, a 1.5 kg ball held at a vertical position of 20 m above the ground has gravitational potential energy. Gravitational Potential Energy (Eg)

  9. Gravitational Potential Energy (Eg) Eg= m * g * h Eg= 1.5kg * 9.8* 20m Eg= 294 J .

  10. Why would a ball on the ground, have no gravitational potential energy? Gravitational Potential Energy(Eg).

  11. TBI for Gravitational Potential Energy (Eg) The higher that an object is elevated, the greater the Eg…

  12. What is Kinetic Energy?

  13. Kinetic Energy is the energy of motion. The amount of Ek depends on the mass and velocity of the object. Kinetic Energy (Ek)

  14. Kinetic Energy (Ek) To calculate the kinetic energy, use the formula… Ek= ½ m * V2 m = mass V = velocity of the object.

  15. If the car has a mass of 1000 kg, and travels at a velocity of 20 m/s, then the Kinetic Energy equals… Kinetic Energy (Ek)

  16. Kinetic Energy (Ek) Ek= ½ m * V2 Ek= ½ 1000kg * (20 m/s)2 Ek= 500 kg * 400 m2/s2 Ek= 200,000 J

  17. The greater the velocity or speed of an object, then the greater the Ek! TBI for Kinetic Energy (Ek)

  18. How do Eg and Ek relate in an energy system?

  19. As the car moves down the track, what happens to the Eg?

  20. As the height is lower, the Eg becomes less.

  21. As the car moves down the track, what happens to the Ek?

  22. The car speeds up, so Ek increases!!!

  23. What is the car’s position on the track when the Eg = Ek? One-half of the distance down the track.

  24. What happens to the Total Mechanical Energy (TME)?

  25. Total Mechanical Energy (TME) TME = Eg + Ek The TME will always remain constant!!

  26. As the pendulum swings, the Eg is transformed into Ek…

  27. but the Total Mechanical Energy (TME) remains constant.

  28. What is the position of the pendulum when all energy is Eg?

  29. The pendulum is at the top and not moving.

  30. What is the position of the pendulum when Ek is the greatest?

  31. The pendulum is at the bottom of the swing and fastest!!

  32. What is the position of the pendulum when Eg = Ek?

  33. The pendulum is ½ way through the drop.

  34. As the coaster travels on the track, the Eg is exchanged for the Ek. but the Total Energy (TME) remains constant.

  35. The BIG IDEA for energy is Total Mechanical Energy in the system is equal to the Eg + Ek….

  36. The Total Energy in the system will always remain constant.

  37. TBI - Energy can not be created or destroyed; it can only be transformed from one type of energy form to another. Conservation of Energy!

  38. Reflection: What are 2things you figured out about energy from this PPT??

  39. Now, Let’s Look at some Energy Graphs

  40. As the swinging pendulum falls…

  41. EgEkTE

  42. EgEkTE

  43. EgEkTE

  44. The Eg is transformed into Ek EgEkTE EgEkTE EgEkTE EgEkTE

  45. EgEkTE but the Total Energy in the system at each position remains constant. EgEkTE EgEkTE EgEkTE

  46. EgEkTE EgEkTE EgEkTE EgEkTE

  47. As the kids on the sled go down the hill… the energy graph would look like this…

  48. EgEkTE

  49. EgEkTE

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