Newton's Lawsof Motion

1. Newton's Lawsof Motion

2. Newton’s Contributions • Calculus • Light is composed of rainbow colors • Reflecting Telescope • Laws of Motion • Theory of Gravitation

3. How many are there?What are they? 3 1) Inertia 2) F=ma 3) Action/Reaction

4. Newton’s First Law(law of inertia) An object at rest tends to stay at rest and an object in motion tends to stay in motion unless acted upon by an unbalanced force.

5. 1st Law “An object at rest tends to stay at rest unless acted upon by an unbalanced force” True or False? An object that is not moving, will not move unless a force acts on it. True

6. An object in motion tends to stay in motion unless acted upon by an unbalanced force. True or False? Will something continue moving in a straight line unless acted upon by an unbalanced force? Example- Full cup of coffee in the cup holder of a car- the car stops, the cup stops, the coffee doesn’t. True

7. Newton’s First Law = Law of Inertia What is the purpose of seat belts and headrests? Answer

9. Newton’s First Law =Law of Inertia What happens when you hit a curb or rock while on a skate board?

10. Simply put…things tend to keep on doing what they are already doing.

11. A question If the force of gravity disappeared between the sun and planets…what type of path would the planets follow?

12. A question *Which has more inertia, a big ship or a little ship?* *Why are linemen so big in football?*

13. How does this affect us?

14. Will an object moving at the same velocity will continue moving at the same velocity unless acted upon by an unbalanced force? Yes

15. Balanced Force Equal forces in opposite directions produce no motion Or motion with a constant velocity

16. Unbalanced Forces Unequal opposing forces produce an unbalanced force causing motion

17. *Net Force…this is easy* • The combination of all forces acting on an object • Determines if the object moves or remains at rest

18. What is the net (total) force? • 3 Newtons, right • 100 Newtons, North

19. If objects in motion tend to stay in motion, why don’t moving objects keep moving forever? Things don’t keep moving forever because there’s almost always an unbalanced force acting upon them. A book sliding across a table slows down and stops because of the force of friction. If you throw a ball upwards it will eventually slow down and fall because of the force of gravity.

20. Newton’s First Law =law of _______ • MASS is the measure of the amount of matter in an object. • It is measured in Kilograms *Mass is the measure of inertia*

21. Newton’s First Law =law of inertia • INERTIA is a property of an object that describes how ______________________ the motion of the object • more _____ means more ____ much it will resist change to mass inertia

22. Mass vs Weight…easily confused with each other • mass is the amount of matter in an object. • weight is a measure of the gravitational pull on an object, depends on location (planet)

23. Mass vs Weight…easily confused with each other

24. What should it say to make sense?

25. What is weight? W= mg

26. A weird fact you need to know SI unit of force (weight) is the Newton unit- N…capitalized because it is named after a person Weight= mg = 1 kg-m/s²

27. Build your own Newton!

28. My Newton’s name is… and is… He/she represents… (Name) looks like… He/she also has traveled to… Overall, (name) is…

29. Day 3

30. * How much does 5 kg of candy canes weigh?* Weight= mg = 5 kg (9.8 m/s²) = 49 Newtons

31. *A woman stands with 2 feet on the bathroom scale and weighs 300 N* *What will the scale read when she lifts one foot off the scale?* 300 Newtons

32. *If you Know N,  9.8 m/s² = mass* Formula: mass=Newtons 9.8 m/s² The mass of a reindeer that weighs 900 N is about….. a) 900 kg b) 9 000 kg c) 90 kg 90 kg

33. *Where would you have the largest mass of a rock if it weighed 1 N, on… a) the moon? b) the Earth? • Jupiter? Formula: mass= Newtons 9.8 m/s² • 1 N/1.6 m/s² = 0.6 kg • 1 N/9.8 m/s² = 0.1 kg • 1 N/ 24.5 m/s² = 0.04 kg

34. Review • WEIGHT is a measure of the force of ________ on the mass of an object • measured in __________ gravity Newtons

36. Newton’s Second Law Force equals mass times acceleration. F = ma

37. Newton’s Second Law • Force = Mass x Acceleration • Force is measured in Newtons ACCELERATION of GRAVITY(Earth) = 9.8 m/s2 • Weight (force) = mass x gravity (Earth) Moon’s gravity is 1/6 of the Earth’s If you weigh 420 Newtons on earth, what will you weigh on the Moon? 70 Newtons If your mass is 41.5Kg on Earth what is your mass on the Moon?

38. Newton’s Second Law One rock weighs 5 Newtons. The other rock weighs 0.5 Newtons. How much more force will be required to accelerate the first rock at the same rate as thesecond rock? Ten times as much

39. Newton’s Third Law For every action there is an equal and opposite reaction.

40. Newton’s 3rd Law • For every action there is an equal and opposite reaction. Book to earth Table to book

41. Think about it . . . What happens if you are standing on a skateboard or a slippery floor and push against a wall? You slide in the opposite direction (away from the wall), because you pushed on the wall but the wall pushed back on you with equal and opposite force. Why does it hurt so much when you stub your toe? When your toe exerts a force on a rock, the rock exerts an equal force back on your toe. The harder you hit your toe against it, the more force the rock exerts back on your toe (and the more your toe hurts).

42. Newton’s Third Law • A bug with a mass of 5 grams flies into the windshield of a moving 1000kg bus. • Which will have the most force? • The bug on the bus • The bus on the bug

43. Newton’s Third Law • The force would be the same. • Force (bug)= m x A • Force (bus)= M x a Think I look bad? You should see the other guy!

44. Action and Reaction on Different Masses Consider you and the earth Action: earth pulls on you Reaction: you pull on earth

45. Action: tire pushes on road Reaction: road pushes on tire

46. Reaction: gases push on rocket Action: rocket pushes on gases

47. Consider hitting a baseball with a bat. If we call the force applied to the ball by the bat the action force, identify the reaction force. (a) the force applied to the bat by the hands (b) the force applied to the bat by the ball (c) the force the ball carries with it in flight (d) the centrifugal force in the swing (b) the force applied to the bat by the ball

48. Newton’s 3rd Law • Suppose you are taking a space walk near the space shuttle, and your safety line breaks. How would you get back to the shuttle?

49. Newton’s 3rd Law • The thing to do would be to take one of the tools from your tool belt and throw it is hard as you can directly away from the shuttle. Then, with the help of Newton's second and third laws, you will accelerate back towards the shuttle. As you throw the tool, you push against it, causing it to accelerate. At the same time, by Newton's third law, the tool is pushing back against you in the opposite direction, which causes you to accelerate back towards the shuttle, as desired.

50. What Laws are represented?