Physics: work, force and energy

work, force and energy

1. PHYSICS: FORCE, ENERGY AND WORK TEACHER: Vergie M. Bateriza

2. PHYSICS: FORCE, ENERGY AND WORK TEACHER: Vergie M. Bateriza

3. LESSON OBJECTIVE Study the concept of force, energy and work and its relationship; Understand how to compute the value of net force value of Mathematically work done situation in a given; and Identify the different conditions for us to say that work is done.

4. FORCE In Physics: force is the push or pull applied on an object.

5. FORCE Force can also change the speed and direction of a moving object.

6. FORCE If enough force is applied, it can also change the shape or size of an object

7. Categories of forces : Contact forces  are those types of forces that result when the two interacting objects are perceived to be physically contacting each other.

8. 2. action-at-a distance force Gravitational force, electrical force, magnetic force

9. BALANCED FORCE forces that are equal in magnitude and in opposite direction so there will be no motion in an object Let us study this illustration: 1. It was observed that a 50 kg object is being pushed to opposite directions, we have observed that a 70 Newton of force is being applied to push the said object to the right and on the other side, the same amount of force is being exerted pushing to the left direction.

10. BALANCED FORCE forces that are equal in magnitude and in opposite direction so there will be no motion in an object Let us study this illustration: 2. The two elephant were pulling a log in an opposite direction using a 200 Newton force.

11. BALANCED FORCE forces that are equal in magnitude and in opposite direction so there will be no motion in an object Let us study this illustration: 3. Suppose two boys are pushing the 190 kg heavy crate with 25 newtons of force to the right and another guy is pushing the said crate to the left with 50 newtons of force to the left, what will be the net force that will act on the object? Will the object move?

12. NET FORCE is the vector sum of forces acting on a particular or body. ADD the values of the forces going to the same direction to get the NET FORCE SUBTRACT the values of the forces going to the opposite direction to get the NET FORCE

13. UNBALANCED FORCE a force where two forces acting in opposing directions on a body, are not equal in magnitude and in size. When force is applied on an object, resulting in the movement of that object work is said to be done. Let us study this illustration: 1. On this illustration it shows that there were three persons pulling the rope to the opposite sides. It is notable that the other group exerted 400 Newton force while the other groups exerts 300 Newton force.

14. UNBALANCED FORCE a force where two forces acting in opposing directions on a body, are not equal in magnitude and in size. When force is applied on an object, resulting in the movement of that object work is said to be done. Let us study this illustration: LEFT RIGHT NETFORCE 400 N 300 N = 100 N To the left

15. UNBALANCED FORCE a force where two forces acting in opposing directions on a body, are not equal in magnitude and in size. When force is applied on an object, resulting in the movement of that object work is said to be done. Let us study this illustration: 1. Joy is pushing the piano going to the right by exerting 35 Newtons force while Joey is pulling the piano to the right by exerting 30 Newton force

16. UNBALANCED FORCE a force where two forces acting in opposing directions on a body, are not equal in magnitude and in size. When force is applied on an object, resulting in the movement of that object work is said to be done. Let us study this illustration: JOY JOEY NETFORCE 35 N 30 N = 65N to the right

17. Difference between BALANCED and UNBALANCED FORCE condition balanced Unbalanced Net force zero Greater than zero Magnitude (forces) equal Not equal direction opposite Same or opposite Objects position At rest Moves in the direction with greater force.

18. Assessment: With your groupmates examine if the illustrations below shows balanced force by yelling “mine” and if it shows unbalanced force yell “yours”. 1.___________

19. Assessment: Tell if the illustrations below shows balanced force by yelling “mine” and if it shows unbalanced force yell “yours”. 2.___________

20. Assessment: Tell if the illustrations below shows balanced force by yelling “mine” and if it shows unbalanced force yell “yours”. 3.___________

21. Assessment: Tell if the illustrations below shows balanced force by yelling “mine” and if it shows unbalanced force yell “yours”. 4.___________

22. Assessment: Tell if the illustrations below shows balanced force by yelling “mine” and if it shows unbalanced force yell “yours”. 5.___________

23. Assessment: With your groupmates examine if the illustrations below shows balanced force by yelling “mine” and if it shows unbalanced force yell “yours”. Lets check!!! Mine 2. Yours 3. Yours 4. Yours 5. Mine

24. Energy In Physics, energy is the capacity to do work

25. Two general types of forces :

26. Kinetic Energy Kinetic energy exists whenever an object which has mass is in motion with some velocity. Everything you see moving about has kinetic energy.  The kinetic energy of an object in this case is given by the relation: KE = (1/2)mv 2 m=mass of the object V=velocity of the object The greater the mass or velocity of a moving object, the more kinetic energy it has.

27. Kinetic Energy The greater the mass or velocity of a moving object, the more kinetic energy it has.

28. Potential Energy Potential energy exists whenever an object which has mass has a position within a force field. The most everyday example of this is the position of objects in the earth's gravitational field. The potential energy of an object in this case is given by the relation: PE = mgh  PE = Energy (in Joules) m = mass (in kilograms) g = gravitational acceleration of the earth (9.8 m/sec2) h = height above earth's surface (in meters)

29. Law of Conservation of Energy Law of Conservation of Energy- Energy can neither be created nor destroyed. Energy is always changing from one kind to another. The total energy of an object never changes.

30. Energy and Work

31. Work Work is the product of the force exerted on the object and the displacement of the object along the direction of the force. (parallel relationship)

32. Work is done For us to say that work is being done, there are three conditions that must be met: There must be a presence of force The object has to move a certain distance called displacement The movement of the object must be in the same direction of the applied force.

33. Activity Let us analyze if the following illustrations shows the concept of work: A man pushing the wall- is there a work done? Conditions Present/absent Presence of force Presence of displacement Parallel relationship of force and displacement

34. Activity Let us analyze if the following illustrations shows the concept of work: A man pushing the wall- is there a work done? Conditions Present/absent Presence of force present Presence of displacement Absent Parallel relationship of force and displacement Absent

35. Activity Let us analyze if the following illustrations shows the concept of work: 2. A man pulling a box-is there a work done? Conditions Present/absent Presence of force Presence of displacement Parallel relationship of force and displacement

36. Activity Let us analyze if the following illustrations shows the concept of work: 2. A man pushing the wall- is there a work done? Conditions Present/absent Presence of force present Presence of displacement present Parallel relationship of force and displacement present

37. Activity Let us analyze if the following illustrations shows the concept of work: 3. A man walking while reading a book -is there a work done? Conditions Present/absent Presence of force Presence of displacement Parallel relationship of force and displacement

38. Activity Let us analyze if the following illustrations shows the concept of work: 3. A man pushing the wall- is there a work done? Conditions Present/absent Presence of force present Presence of displacement present Parallel relationship of force and displacement absent

39. Let us compute mathematically the value of work in a situation

40. Lets try to solve this!

41. Lets try to solve this!

42. Lets try to solve this!

43. Lets try to solve this!

44. Lets try to solve this!

45. Lets try to solve this!

46. Lets try to solve this!

47. What is the underlying relationship between force-energy-and-work? When force is applied and the object move in parallel direction with the applied force work is done. In order for anyone or anything to do work it must have energy. In doing work, energy is transferred. When the object does the work it losses energy and when the object is done on the object it gains energy.

48. Assessment: Tell if the illustrations below shows work is done by writing “mine” and if it shows work is not done write “yours” on your answer sheet 1 2 3 4

49. Assessment:

50. Assignment : At home, list down at least 5 real life scenarios. Ask your family members to portray the scenario, take a picture and print it in a long bond paper. Label each picture by using an arrow that represent the force applied, and the displacement of the object.