What are Kinetic and Potential Energy?

1. What are Kinetic and Potential Energy?

2. What is ENERGY? • Energy is the ability to do work. • Everything that happens in the world uses energy! • Most of the time we can’t see energy, but it is everywhere around us!

3. Energy means that • birds can fly, • tigers can roar, • wind can blow, • sun can shine, • cars can go fast, • factories can make things, • light bulbs can glow and • your computer can work. Without energy, there would be nothing: no life, no movement, no light, … nothing

4. Energy… • is NEVER created or destroyed! • can only be STORED or TRANFERRED.

5. Forms of Energy Chemical Sound Radiant Electrical Mechanical Magnetic Thermal Nuclear Main Menu

6. This car uses a lot of energy Batteries store energy! We get our energy from FOOD! Even this sleeping puppy is using stored energy.

7. Remember: ALL matter is made up of particles. The particles NEVER stop moving.

8. What is Kinetic Energy? • Energy an object has due to its motion • K.E. = .5(mass x speed2)

9. Kinetic Energy Is… • The energy of a moving object. • "Kinetic" means movement! • When stored energy is being used up, it is making things move or happen.

10. Examples of Kinetic Energy:

11. The faster the object moves, the more kinetic energy is produced. • The greater the mass and speed of an object, the more kinetic energy there will be.

12. When these objects move at the same speed, which will have more kinetic energy?

13. ANSWER The semi- truck has more mass; therefore, more kinetic energy!

14. An object has the MOST kinetic energy when it’s movement is the GREATEST. • When an object has the LEAST potential energy, it has the MOST kinetic energy.

15. A water bottle is knocked off a desk.When does the bottle have the MOST kinetic energy? A. At the top of the fall. B. In the middle of the fall. C. At the bottom of the fall.

16. C. At the bottom of the fall. • It has the most kinetic energy when its movement and speed are greatest, which is at the bottom of the fall right before it hits the ground. • When an object has the LEAST potential energy is when it has the MOST kinetic energy. BrainPop

17. Kinetic Energy= the energy an object possesses because of its motion • The amount of Kinetic energy is dependent on the mass of the object in motion and it’s velocity.

18. Objects "tend to keep on doing what they're doing" • In fact, it is the natural tendency of objects to resist changes in their state of motion. • Without some outside influence, an object in motion will remain in motion and an object at rest will remain at rest.

19. Cardboard and a Coin placed on an Empty Tumbler Flick the cardboard with the finger. What do you observe? The coin drops into the tumbler. When we flick the cardboard the cardboard moves fast whereas the coin continues in its state of rest and hence drops into the tumbler. This tendency to resist changes in their state of motion is described as inertia Cardboard and a coin placed on an empty glass Flick the cardboard with the finger. What do you observe? The coin drops into the tumbler. When we flick the cardboard the cardboard moves fast whereas the coin continues in its state of rest and hence drops into the glass. So it is clear that objects continue to remain in their state of rest or of uniform motion until an external force is applied.

20. Examples of Inertia of Rest A passenger standing in a bus leans backwards when the bus starts all of a sudden Fruits fall down when the branches of a tree are shaken Dust particles on a carpet falls when we beat the carpet with a stick Examples of Inertia of Motion A passenger standing in a moving bus leans forward when the bus stops all of a sudden A man carelessly stepping out of a moving train onto the ground leans forward Example of Inertia of Direction The water particles sticking to the cycle tire are found to fly off tangentially Inertia of a body depends upon its mass. That is, massive objects possess more inertia than lighter ones.

21. Potential Energy is… • The energy stored in an object. • "Potential" simply means the energy has the ability to do something useful later on.

22. Potential Energy • The energy of position • The amount of energy contained in an object at rest

23. What is Potential Energy? • Energy that is stored and waiting to be used later

24. What is Gravitational Potential Energy? • Potential energy due to an object’s position • P.E. = mass x height x gravity Don’t look down, Rover! Good boy!

25. What is Elastic Potential Energy? • Potential energy due compression or expansion of an elastic object. Notice the ball compressing and expanding

26. What is Chemical Potential Energy? • Potential energy stored within the chemical bonds of an object

27. Examples of Potential Energy: A stretched rubber band.. Water at the top of a waterfall.. Yo–Yo held in your hand.. A drawn Bow and Arrow…

28. The higher an object, the more potential energy. • The more mass an object has, the more potential energy it has.

29. Which object has more potential energy? B A

30. ANSWER A This brick has more mass than the feather; therefore more potential energy!

31. Changing an objects’ height can change its potential energy. • If I want to drop an apple from the top of one of these three things, where will be the most potential energy? A C B

32. ANSWER • The higher the object, the more potential energy! A

35. Potential Energy Converted to Kinetic Energy… • When stored energy begins to move, the object now transfers from potential energy into kinetic energy.

36. Roller Coasters • When does the train on this roller coaster have the MOST potential energy? • AT THE VERY TOP! • The HIGHER the train is lifted by the motor, the MORE potential energy is produced. • At the top of the hill the train has a huge amount of potential energy, but it has very little kinetic energy.

37. As the train accelerates down the hill the potential energy is converted into kinetic energy. • There is very little • potential energy at the bottom of the hill, but there is a great amount of kinetic energy.

38. When does the train on this roller coaster have the MOST kinetic energy? (When is it moving the fastest?) (When does it have the LEAST potential energy???) • At the bottom of the tallest hill!

39. Animated Roller Coaster

40. Roller coaster

41. Conversion of Potential to Kinetic Energy • In this picture both kinds of energy are evident. Can you point them out?

42. The water at the top has potential energy • When water falls to a lower level, the potential energy is converted to kinetic energy.

43. Notes • All energy is divided into two types: potential and kinetic. • Potential Energy: The energy stored in an object. • Kinetic Energy: The energy of a moving object. • Energy is never created or destroyed. It is always stored or transferred.