1. Energy

2. “What is Energy?” Energy is what makes things ‘happen’ (turning the lights on, driving a car, using a Bunsen, etc.) Energy is measured in ______. There are many different forms of energy.

13. “Energy” has many different forms: Light energy Heat energy Sound energy Electrical energy Radiation energy Kinetic energy Nuclear potential energy Chemical potential energy Gravitational potential energy Elastic potential energy

14. Energy Transformations and the Law of Conservation of Energy

21. Law of Conservation of Energy Energy can neither be created nor destroyed. Energy can only be transformed (change its form) or transferred (change its location)

23. The three main forms of Energy in Y12 Physics: 1. Kinetic Energy 2. Gravitational Potential Energy 3. Elastic Potential Energy

24. Kinetic Energy m = mass of the moving object v = speed of the moving object

26. Gravitational Potential Energy m = mass of the moving object g = acceleration due to gravity (9.8 ms -2 ↓) h = height of the object

28. Example: E K & E P Transformation A 24 kg rock is dropped from the top of a cliff. The instantaneous speed of the rock at the bottom of the fall is 24.5 ms -1. a)Calculate the kinetic energy of the rock at the bottom. b)Where did the kinetic energy come from? c)Calculate the height of the rock’s fall.

29. Elastic Potential Energy & Hooke’s Law

30. Elastic Potential Energy k = spring constant x = length of stretch (or compression)

31. Hooke’s Law or F = force applied on the stretchy object x = length of stretch (or compression) k = spring constant (measured in ____ )

32. Example: a)A mass of 0.5 kg hung from the end of a spring extends the spring by 25 cm. Calculate the spring constant. b)If another mass of 0.5 kg is added, how long would the spring extend by?

33. Example: A 80 kg child stands on a trampoline and causes the trampoline to sag by 1 m. a)Calculate the trampoline’s spring constant b)Calculate the elastic potential energy stored in the trampoline

34. Gravitational Potential Energy Kinetic Energy Elastic Potential Energy

38. Force (N) Compression (cm) By using Hooke’s Law and the graph shown, work out the spring’s Spring Constant.

39. Worksheet NINE