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# Force and motion

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การฝึกอบรมเชิงปฏิบัติการการสอนวิทยาศาสตร์และคณิตศาสตร์ด้วยภาษาอังกฤษ

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### Force and motion

1. 1. What causes an object to move?  A FORCE!  ALL motion is due to forces acting on objects! What is a force?  A push or a pull MOTION
2. 2. Motion  What is motion?  A change in the position of an object over time.  How do you know something has moved?  You use a reference point!  A stationary (not moving) object such as a tree, street sign, or a line on the road. Did the beaver move?
3. 3. Can more than one force act on an object at the same time? #2 #3 #1 YES! Example: Gravity is pulling you down to Earth, the ground is supporting you, and your legs moving you forward as you run during PE. The total combination of the forces acting on an object is called NET FORCE.
4. 4. Balanced Forces  A balanced force is one in which the net force equals ZERO.  Do you think there will be any motion?  NO!  Examples: 25 Newtons 25 Newtons
5. 5. Unbalanced Forces  An unbalanced force is one in which the net force is greater than zero.  Do you think there will be any motion?  YES!  Examples: 25 Newtons 40 Newtons 2 N 50 N
6. 6. Only an _______________ force can change the motion of an object. Example: Your doggy can cause you to move if he pulls with enough force.  His force is greater than the force you’re using to stay in place
7. 7. What would happen if an unbalanced force acted on an object that’s already in motion?  It will change the speed or direction of the object.  Example: Your sisther is driving her car. You run up behind her and give her a push.  Your force adds to the existing force causing her to speed up.
8. 8. Unbalanced forces can act in the same direction.  Example: You’re pushing a cabinet across the room with a force of 15 N. You’re friend is pulling with a force of 10 N.  What is the NET FORCE?  What direction is the cabinet moving? 15 Newtons 10 Newtons
9. 9. Unbalanced forces can act in opposite directions.  Example: Six people are tugging on a rope. Three people pulls with a force of 20N and the other pulls with a force of 25N.  What is the NET FORCE?  What direction is the rope moving? 25 Newtons20 Newtons
10. 10. Friction and Gravity  What is friction?  A force that opposes the motion of an object  It’s a “contact” force!  Occurs when an object in motion rubs against a surface.  The contact reduces the speed of the object and releases heat.
11. 11. What affects the amount of friction?  The force of the push/pull  The harder you push, the longer it’s going to take friction to stop the object.  The bumpiness of the surface  The rougher the surface, the more friction.  The weight of the object  The heavier the object, the more friction.
12. 12.  What is gravity?  The force of attraction between all objects.  The amount of gravity depends on two things:  The objects’ masses  The distance between the two objects
13. 13.  Since the earth is so large, everything on it is attracted to it even if they’re not touching!  Example: Apple fall  Apple fall because the gravity of the earth.
14. 14. 1. What is the net force on the box shown below? a)10 N to the left b) 10 N to the right c) 60 N to the left d) 50 N to the right 10 N 10 N 10 N Questions Choose the correct item.
15. 15. 1. What is the net force on the box shown below? a)10 N to the left b) 10 N to the right c) 60 N to the left d) 50 N to the right 10 N 10 N 10 N Questions Choose the correct item.
16. 16. 2 .Which force always pulls downward on objects? a) Support force b) Friction force c) Gravity d) Air resistance
17. 17. 2 .Which force always pulls downward on objects? a) Support force b) Friction force c) Gravity d) Air resistance
18. 18. 3.A force is described as... a) A push only b) A pull only c) A push or a pull d) None of the above
19. 19. 3.A force is described as... a) A push only b) A pull only c) A push or a pull d) None of the above
20. 20. 4. A change to an objects motion is caused by... a) Balanced forces b) Unbalanced forces c) Acceleration d) Velocity
21. 21. 4. A change to an objects motion is caused by... a) Balanced forces b) Unbalanced forces c) Acceleration d) Velocity
22. 22. 5.Describe the motion of a person not wearing a seat belt if the car stops suddenly. a) The person and car will stop together. b) The person will stop faster than the car because they are lighter. c) The car will stop and the person will keep moving forward because of inertia. d) The car will stop and the person will speed up.
23. 23. 5.Describe the motion of a person not wearing a seat belt if the car stops suddenly. a) The person and car will stop together. b) The person will stop faster than the car because they are lighter. c) The car will stop and the person will keep moving forward because of inertia. d) The car will stop and the person will speed up.
24. 24. 6.A falling object is pulled down by the earth. The earth is pulled up toward the object. Why doesn’t the earth move? a) Only the earth has gravity. b) The Earth has a very large mass and a small acceleration. c) The Earth has a very small mass and a large acceleration. d) Air resistance gets in the way.
25. 25. 6.A falling object is pulled down by the earth. The earth is pulled up toward the object. Why doesn’t the earth move? a) Only the earth has gravity. b) The Earth has a very large mass and a small acceleration. c) The Earth has a very small mass and a large acceleration. d) Air resistance gets in the way.
26. 26. 7.What forces are acting on a dropped book that falls to the floor? a) Gravity only b) Gravity and air resistance c) Air resistance d) Friction only
27. 27. 7.What forces are acting on a dropped book that falls to the floor? a) Gravity only b) Gravity and air resistance c) Air resistance d) Friction only
28. 28. 8.Which ball will hit the ground first? wood ball Plastic ball metal ball a) Metal first, then plastic, then wood last b) Wood first , then plastic, then metal last c) They will all hit at the same time. d)There is no way to tell.
29. 29. 8.Which ball will hit the ground first? wood ball Plastic ball metal ball a) Metal first, then plastic, then wood last b) Wood first , then plastic, then metal last c) They will all hit at the same time. d)There is no way to tell.
30. 30. 9. A duck flies 60 meters in 10 seconds. What is the duck’s speed? a) 600 m/s b) 50 m/s c) 6 m/s d) 70 m/s
31. 31. 9. A duck flies 60 meters in 10 seconds. What is the speed? a) 600 m/s b) 50 m/s c) 6 m/s d) 70 m/s
32. 32. 10.What unit do scientists use to measure force? a) Newton b) Grams c) Meters d) Meter per second per second
33. 33. 10.What unit do scientists use to measure force? a) Newton b) Grams c) Meters d) Meter per second per second
34. 34. 11.This test paper is sitting at rest on your desk. Which of the following statements best describes this situation? a)There are no forces acting on your paper. b)Your paper pushes on the desk only. c)The desk pushes on your paper only d)The forces acting on the paper are balanced.
35. 35. 11.This test paper is sitting at rest on your desk. Which of the following statements best describes this situation? a)There are no forces acting on your paper. b)Your paper pushes on the desk only. c)The desk pushes on your paper only d)The forces acting on the paper are balanced.
36. 36. 12. A beetle crawls 2 cm/minute for ten minutes. How far did it crawl? a) 8 centimeters b) 5 centimeters c) 2 centimeters d) 20 centimeters
37. 37. 12. A beetle crawls 2 cm/minute for ten minutes. How far did it crawl? a) 8 centimeters b) 5 centimeters c) 2 centimeters d) 20 centimeters
38. 38. 13.When you slide a box across the floor what force must your push be stronger than? a) Support force b) Friction force c) Gravity d) Air resistance
39. 39. 13.When you slide a box across the floor what force must your push be stronger than? a) Support force b) Friction force c) Gravity d) Air resistance
40. 40. 14.The moon has a smaller mass than the Earth. If you were able to travel to the moon your weight would... a) Increase b) Decrease c) Stay the same d) Vary with day and night
41. 41. 14.The moon has a smaller mass than the Earth. If you were able to travel to the moon your weight would... a) Increase b) Decrease c) Stay the same d) Vary with day and night
42. 42. Group Force  Mr.Weerachat Martluplao  Miss.Mookda Bannabuppha  Mrs.Ganyarath Prommakoon Workshop Science and Match Teaching Training in Engilish Program