2. Newton’s Laws of Motion I. Law of Inertia II. F=ma III. Action-Reaction

3. Newton’s Laws of Motion 1 st Law – An object at rest will stay at rest, and an object in motion will stay in motion at constant velocity, unless acted upon by an unbalanced force. 1 st Law – An object at rest will stay at rest, and an object in motion will stay in motion at constant velocity, unless acted upon by an unbalanced force. 2 nd Law – Force equals mass times acceleration. 2 nd Law – Force equals mass times acceleration. 3 rd Law – For every action there is an equal and opposite reaction. 3 rd Law – For every action there is an equal and opposite reaction.

4. 1 st Law of Motion (Law of Inertia) An object at rest will stay at rest, and an object in motion will stay in motion at constant velocity, unless acted upon by an unbalanced force.

5. Inertia…  Inertia is the tendency of an object to resist changes in its velocity: whether in motion or motionless.  Basically, an object will remain at a constant speed unless disturbed.

6. 1 st Law  Could an object move forever?  No, because an unbalanced force of gravity and friction will friction will always act on it always act on it

7. There are four main types of friction: There are four main types of friction: Sliding friction: Sliding friction: when two objects slide past each other when two objects slide past each other Examples: Ice Skating, pushing book across table Examples: Ice Skating, pushing book across table Rolling friction: Rolling friction: When something round rolls over a surface When something round rolls over a surface Examples: Wheels on ground, cartilage over bone Examples: Wheels on ground, cartilage over bone

8. Fluid friction (air or liquid): Fluid friction (air or liquid): When an object moves through the air or water When an object moves through the air or water Examples: Airplane, Boat Examples: Airplane, Boat Static friction: Static friction: When two objects are touching but resist moving When two objects are touching but resist moving Examples: pushing a heavy bookcase Examples: pushing a heavy bookcase

9. No Friction vs. Friction  In the absence of friction, an item will continue moving forever.  Because of friction, items will slow on their own, their own, unless they unless they are stopped are stopped first! first!

10. Momentum…  The force of a moving body or the measure of the motion of a body

11. Momentum  Momentum = mass x velocity (P=m x v)  Since it has velocity, it includes direction!!!  Mass:  Larger mass = more momentum  Smaller mass = less momentum  Velocity:  Higher velocity = more momentum  Slower velocity = less momentum

12. Using Momentum Formula… 1. A 1000 kg car is traveling south at 14 m/s. Calculate the momentum of the car. Givens? Unknown? Givens? Unknown? Mass = 1000 kg Momentum = ? Mass = 1000 kg Momentum = ? Velocity = 14 m/s South Velocity = 14 m/s South Formula? Formula? P = M x V P = M x V P = (1000 kg) x (14 m/s) P = (1000 kg) x (14 m/s) P = 14000 kg-m/s South P = 14000 kg-m/s South

13. RECAP… 2. Calculate the momentum of a 16 kg bicycle traveling north at 3 m/s. Givens? Unknown? Givens? Unknown? Mass = 16 kg Momentum = ? Mass = 16 kg Momentum = ? Velocity = 3 m/s North Velocity = 3 m/s North Formula? Formula? P = M x V P = M x V P = (16 kg) x (3 m/s) P = (16 kg) x (3 m/s) P = 48 kg-m/s North P = 48 kg-m/s North

14. RECAP… What is the speed of a train with a mass of 18,000 kg and a momentum of 234,000 kg-m/s West. What is the speed of a train with a mass of 18,000 kg and a momentum of 234,000 kg-m/s West. Givens? Unknown? Givens? Unknown? Mass = 18000 kg Speed = ? Mass = 18000 kg Speed = ? Momentum = 234000 kg-m/s Momentum = 234000 kg-m/s Formula? Formula? S = P/ M S = P/ M S = (234,000 kg-m/s) / (18000 kg) S = (234,000 kg-m/s) / (18000 kg) S = 13 m/s S = 13 m/s

15. RECAP… What is the mass of a bicycle with a velocity of 2 m/s east and a momentum of 24 kg-m/s East. What is the mass of a bicycle with a velocity of 2 m/s east and a momentum of 24 kg-m/s East. Givens? Unknown? Givens? Unknown? Velocity = 2 m/s East Mass = ? Velocity = 2 m/s East Mass = ? Momentum = 24 kg-m/s Momentum = 24 kg-m/s Formula? Formula? M = P/ V M = P/ V M = (24 kg-m/s) / (2 m/s East) M = (24 kg-m/s) / (2 m/s East) M = 12 kg M = 12 kg

16. RECAP… A 223.25 kg motorcycle is moving at a speed of 105.75 m/s towards home. What is the momentum of the cycle? A 223.25 kg motorcycle is moving at a speed of 105.75 m/s towards home. What is the momentum of the cycle? Givens? Unknown? Givens? Unknown? Mass = 223.25 kg Momentum = ? Mass = 223.25 kg Momentum = ? Speed = 105.75 m/s Speed = 105.75 m/s Formula? Formula? P = M x V P = M x V P = (223.25 kg) x (105.75 m/s) P = (223.25 kg) x (105.75 m/s) P = 23608.69 kg-m/s to home P = 23608.69 kg-m/s to home

17. Conservation of Momentum…  When objects collide, the momentum has to go somewhere….right?

18. Conservation of Momentum…  When objects collide, the momentum has to go somewhere….right?

19. Conservation of Momentum…  When objects collide, the momentum has to go somewhere….right?

20. Conservation of Momentum…  The momentum is never lost…for a collision occurring between object 1 and object 2, the total momentum before the collision is equal to the total momentum after the collision.  OR…Momentum is conserved and it can either be retained or passed to the item being hit

21. Newtons’s 1 st Law and You Don’t let this be you. Wear seat belts. Because of inertia, objects (including you) resist changes in their motion. When the car going 80 km/hour is stopped by the brick wall, your body keeps moving at 80 m/hour.

22. RECAP… So, in a nutshell, what is Newton’s 1 st Law? So, in a nutshell, what is Newton’s 1 st Law?

23. Newton’s 2 nd Law

24.  The net force of an object is equal to the product of its mass and acceleration, or F=ma. OR  An object that has a force acting on it will change its speed.

25. SYMBOLSTANDS FORMEASURED IN FNet ForceNewtons MMassKilograms AAccelerationMeters/Second 2

26. Newton’s 2 nd Law When mass is in kilograms and acceleration is in m/s/s, the unit of force is in newtons (N). When mass is in kilograms and acceleration is in m/s/s, the unit of force is in newtons (N). One newton is equal to the force required to accelerate one kilogram of mass at one meter/second/second. One newton is equal to the force required to accelerate one kilogram of mass at one meter/second/second. mass of the club acceleration of the club force of the club

27. Newton’s 2 nd Law Force is the push or pull that causes a change in motion of an object Force is the push or pull that causes a change in motion of an object Net force is the total amount of forces acting on an object Net force is the total amount of forces acting on an object You must subtract the forces that cancel out You must subtract the forces that cancel out Force of gravity Force of muscles

28. Net Force Example A Net Force = _______________________ Net Force = _______________________ Direction of Force = ________________ Direction of Force = ________________

29. Net Force Example B Net Force = _______________________ Net Force = _______________________ Direction of Force = ________________ Direction of Force = ________________ 30 N 200 N

30. Net Force Example C Net Force = _______________________ Net Force = _______________________ Direction of Force = ________________ Direction of Force = ________________

31. 2 nd Law (F = m x a) How much force is needed to accelerate a 1400 kilogram car 2 meters per second/per second? Write the formula Write the formula F = m x a Fill in given numbers and units Fill in given numbers and units F = 1400 kg x 2 meters per second/second Solve for the unknown Solve for the unknown 2800 kg-meters/second/second or 2800 N

32. Newton’s 2 nd Law proves that different masses accelerate to the earth at the same rate, but with different forces. We know that all objects, regardless of their mass, accelerate to the ground at the same rate. However, because of the 2 nd Law we know that they don’t hit the ground with the same force. F = ma 98 N = 10 kg x 9.8 m/s/s F = ma 9.8 N = 1 kg x 9.8 m/s/s

34. Check Your Understanding 1. What acceleration will result when a 12 N net force applied to a 3 kg object? A 6 kg object? 1. What acceleration will result when a 12 N net force applied to a 3 kg object? A 6 kg object? 2. A net force of 16 N causes a mass to accelerate at a rate of 5 m/s 2. Determine the mass. 2. A net force of 16 N causes a mass to accelerate at a rate of 5 m/s 2. Determine the mass. 3. How much force is needed to accelerate a 66 kg skier 1 m/sec/sec? 3. How much force is needed to accelerate a 66 kg skier 1 m/sec/sec? 4. What is the force on a 1000 kg elevator that is falling freely at 9.8 m/sec/sec? 4. What is the force on a 1000 kg elevator that is falling freely at 9.8 m/sec/sec?

35. Check Your Understanding 1. What acceleration will result when a 12 N net force applied to a 3 kg object? 1. What acceleration will result when a 12 N net force applied to a 3 kg object? 12 N = 3 kg x 4 m/s/s 12 N = 3 kg x 4 m/s/s 2. A net force of 16 N causes a mass to accelerate at a rate of 5 m/s 2. Determine the mass. 2. A net force of 16 N causes a mass to accelerate at a rate of 5 m/s 2. Determine the mass. 16 N = 3.2 kg x 5 m/s/s 16 N = 3.2 kg x 5 m/s/s 3. How much force is needed to accelerate a 66 kg skier 1 m/sec/sec? 3. How much force is needed to accelerate a 66 kg skier 1 m/sec/sec? 66 kg-m/sec/sec or 66 N 4. What is the force on a 1000 kg elevator that is falling freely at 9.8 m/sec/sec? 4. What is the force on a 1000 kg elevator that is falling freely at 9.8 m/sec/sec? 9800 kg-m/sec/sec or 9800 N 9800 kg-m/sec/sec or 9800 N

36. 3 rd Law For every action, there is an equal and opposite reaction. For every action, there is an equal and opposite reaction.

37. 3 rd Law According to Newton, whenever objects A and B interact with each other, they exert forces on each other. When you sit in your chair, your body exerts a downward force on the chair and the chair exerts an upward force on your body.

38. 3 rd Law  There are two forces resulting from this interaction - a force on the chair and a force on your body.  These two forces are called action and reaction forces.  Action Force = you pushing on chair  Reaction Force = chair pushing on you

39. Newton’s 3rd Law in Nature Consider the movement of a fish through the water. A fish uses its fins to push water backwards. In turn, the water reacts by pushing the fish forwards, propelling the fish through the water. Consider the movement of a fish through the water. A fish uses its fins to push water backwards. In turn, the water reacts by pushing the fish forwards, propelling the fish through the water. The size of the force on the water equals the size of the force on the fish; the direction of the force on the water (backwards) is opposite the direction of the force on the fish (forwards). The size of the force on the water equals the size of the force on the fish; the direction of the force on the water (backwards) is opposite the direction of the force on the fish (forwards).

40. Consider the flying motion of birds. A bird flies by use of its wings. The wings of a bird push air downwards. In turn, the air reacts by pushing the bird upwards. Consider the flying motion of birds. A bird flies by use of its wings. The wings of a bird push air downwards. In turn, the air reacts by pushing the bird upwards. The size of the force on the air equals the size of the force on the bird; the direction of the force on the air (downwards) is opposite the direction of the force on the The size of the force on the air equals the size of the force on the bird; the direction of the force on the air (downwards) is opposite the direction of the force on the bird (upwards). Action-reaction Action-reaction force pairs make it possible for birds to fly.

41. Other examples of Newton’s Third Law The baseball forces the bat to the left (action); the bat forces the ball to the right (reaction). The baseball forces the bat to the left (action); the bat forces the ball to the right (reaction).

42. RECAP: Newton’s 1 st Law An item at rest will stay at rest and an item in motion will stay in motion unless acted on by an unbalanced force. So Basically… An item will continue to move or sit still until something causes it to change

43. RECAP: Newton’s 2 nd Law The net force of an object is equal to the product of its mass and acceleration, or F = ma So Basically… An object that has a force acting on it will change its speed

44. RECAP: Newton’s 3 rd Law For every action there is an equal and opposite reaction So Basically… When object A puts a force on object B, B will put a force on A.

45. Action/Reaction Pairs Newton’s 3 rd Law For every action, there is an equal and opposite reaction….which means every time an item touches another, there is a force applied. For every action, there is an equal and opposite reaction….which means every time an item touches another, there is a force applied. In the following examples, list the action/reaction pairing(s) provide. In the following examples, list the action/reaction pairing(s) provide. REMEMBER: REMEMBER: Items MUST TOUCH in order for there to be considered an action/reaction pair. Items MUST TOUCH in order for there to be considered an action/reaction pair. MUST ALWAYS INCLUDE DIRECTION OF MOVEMENT MUST ALWAYS INCLUDE DIRECTION OF MOVEMENT

46. List the Action/Reaction Pairing(s) Bowling ball pushes pin right, pin pushes bowling ball left Bowling ball pushes pin right, pin pushes bowling ball left

47. List the Action/Reaction Pairing(s) Hammer pushes nail down, nail pushes hammer up Hammer pushes nail down, nail pushes hammer up

48. List the Action/Reaction Pairing(s) Air pushes balloon outward, balloon pushes air inward Air pushes balloon outward, balloon pushes air inward Any more pairings? Any more pairings?

49. List the Action/Reaction Pairing(s) Girl pushes floor down, floor pushes girl up Girl pushes floor down, floor pushes girl up Any more? Any more?

50. List the Action/Reaction Pairing(s) Panda pushes down on log, log pushes up on panda Panda pushes down on log, log pushes up on panda

51. List the Action/Reaction Pairing(s) Ball pushes face right, face pushes ball left Ball pushes face right, face pushes ball left

52. List the Action/Reaction Pairing(s) Blue player pushes gold player right, gold player pushes blue player left Blue player pushes gold player right, gold player pushes blue player left

53. List the Action/Reaction Pairing(s) 1 2-5 6 78 9-12 13 14 15 How many pairings do you see in this picture? How many pairings do you see in this picture?

54. List 3 Action/ Reaction Pairings in the below picture.