Newton's Law of Motion and Friction in Golf

1. Chapter 10 Section 1 http://www.nbclearn.com/science-of-golf Newton’s Third Law of Motion and Momentum

2. GPS Standards • S8P3b. Demonstrate the effect of balanced and unbalanced forces on an object in terms of gravity, inertia, and friction. • S8P5a. Recognize that every object exerts gravitational force on every other object and that the force exerted depends on how much mass the objects have and how far apart they are.

4. Force: • Is a push or pull • Is measured in Newtons (N) • Acts on all objects • Doesn’t necessarily mean that motion will occur • Net force is the force that results from combining all the forces exerted on an object. • http://www.youtube.com/watch?v=y2Gb4NIv0Xg&list=PLA5204D9A75010B6C

5. Forces in the same direction: • You add forces together to determine the net force. Ex. When one person is pushing an object while another is pulling it in the same direction.

7. Forces in different directions: • You subtract the smaller force from the larger force to find the net force. Ex. Children playing tug-of-war

8. Types of Forces • Balanced forces do not change the motion of an object, but if the combination of forces acting on an object are not balanced, then the net force is greater than zero and the motion of the object changes. • Unbalanced forces change the motion of an object.

9. Unbalanced forces • Unbalanced forces produce a change in motion. These forces occur when the net force on an object is NOT zero. • Unbalanced forces are necessary to cause a non-moving object to start moving, and to change the motion of moving objects. • Ex. Playing soccer

12. Balanced forces have a net force of zero. They do not cause a nonmoving object to start moving,and do not cause a change in the motion of a moving object. Ex. *Light fixture hanging from a ceiling. *House of cards Balanced Forces

13. Balanced Force • If all the forces acting on the object are balanced, the net force is zero and the motion of the object does not change. • If an object is already at rest, it will remain at rest. • If an object is moving, it will keep on moving

20. Chapter 10 Section 2 Remediation Video http://www.youtube.com/watch?v=C7NPD9W0kro

22. Friction • Is a force that opposes motion between two surfaces that are touching • The strength of the force of the friction depends on two things: • 1. how hard the surfaces push together • 2. the types of surfaces involved • Friction acts in a direction opposite to the direction of the object’s motion. • http://schayerscience.pbworks.com/w/page/14814672/Got%20Friction Mythbusters Video

23. Phone Book Experiment http://www.youtube.com/watch?v=5heqWHcNwoY Start at 2:07 • Science of Golf: Friction and Spin http://www.nbclearn.com/science-of-golf

25. The rougher the surface, the greater the friction. Ex. Pavement is rougher than grass. • The more force on object puts on another, the greater the friction. Less massive objects exert less force on surfaces than more massive objects do. • Changing the amounts of the surfaces that touch does not change the amount of friction.

26. Types of friction • Sliding friction: very effective at opposing the movement of objects. A lot of force must be exerted to overcome sliding friction. Ex. Sliding a dresser across room, applying brakes on car, writing, etc. • Rolling friction: force is usually less than the force of sliding friction. It is easier to move objects on wheels than it is to slide them. Ex. Cars, bicycles, skates, trains • http://www.youtube.com/watch?v=5JbnDXw-0pM

27. Fluid friction: opposes the motion of objects traveling through a fluid. “Fluid” includes liquids and gases. Ex. Fluid friction between air and fast moving car • Static friction: when a force is applied to an object but does not cause the object to move. The force of the static friction balances the force applied. Static friction disappears as soon as an object starts moving, and then another type of friction occurs. • See fig. 15 p. 122 • http://www.youtube.com/watch?v=FrCvwljoIr0

28. Friction can be harmful. Ex. Car parts overheating and wearing down; can cause holes in your socks and knees of your jeans; can cause erosion of topsoil (by water or wind); • Friction can be helpful. Ex. Helps you to write with your pencil; helps you to walk without slipping

29. Ways to reduce friction: 1. Lubricants such as motor oil, wax, and grease 2. By switching from sliding friction to rolling friction. Ex. Ball bearings

30. Ways to increase friction: 1. Make surfaces rougher. Ex. Batting gloves for baseball players; sand scattered on icy roads 2. Increase the force pushing the surfaces together. Ex. Putting a rock on a piece of paper to keep it from blowing away; scrubbing a pan harder

31. We want better gas mileage? How do we get it? REDUCE FRICTION!

32. What types of friction are the following slides of?

36. Chapter 10 Section 3 Newton’s Three Laws of Motion http://www.youtube.com/watch?v=PkAO8F-Tm-w

37. Newton had hair like a boss…

38. Science of Golf and FootballNewton’s Laws • http://www.nbclearn.com/portal/site/learn/science-of-nfl-football • Newton’s first and second laws and third law and momentum • http://www.nbclearn.com/science-of-golf

39. Newton’s First Law An object at rest remains at rest and an object moving at a constant velocity will continue moving at a constant velocity, unless it is acted upon by an unbalanced force. Law of Inertia http://www.nbclearn.com/science-of-golf

40. Newton’s 1st Law • Newton’s first law of motion states that: • an object at rest will stay at rest unless it is acted upon by an unbalanced force. • an object in motion will continue to move in the same direction and with the same speed unless acted upon by an unbalanced force.

41. Inertia http://www.youtube.com/watch?v=7LGi-Dlb8Vs • Inertia is the tendency of an object to resist a change in motion. • Newton’s first law of motion is also called the law of inertia. • Ex. When the car stops and you keep going forward.

42. Inertia Cont’d Some objects have more inertia than others. It is harder to move a big elephant than a smaller elephant because the bigger elephant has more mass. The greater the mass of an object is, the greater its inertia, and the greater the force required to change is motion.

43. 2nd Law of Motion Newton’s 2nd Law • The acceleration of an object depends on the object’s mass and on the net force acting on the object. Acceleration=net force mass Net force= mass *acceleration http://www.youtube.com/watch?v=dQmYBF_Sd8I&list=PLA5204D9A75010B6C http://www.youtube.com/watch?v=nJTKiS444BQ

44. Acceleration and mass change in opposite ways. An increase in mass causes a decrease in acceleration and an decrease in mass causes a increase in acceleration.

45. Newton’s Third Law • If one object exerts a force on another object, then the second object exerts a force of equal strength in the opposite direction on the first object.

46. Newton’s 3rd Law Another way to say this is: For every action there is an equal but opposite reaction. Dog Circus Activity

48. Conservation of Momentum • The law of conservation of momentum states that, in the absence of outside forces, the total momentum of objects that interact does not change. • The total momentum of any group of objects remains the same, or is conserved, unless outside forces act on the objects. • Teacher Tube

49. Newton’s Cradle • http://www.youtube.com/watch?v=_AH4w-2mxjg • http://www.youtube.com/watch?v=BiLq5Gnpo8Q • http://www.youtube.com/watch?v=OuA-znVMY3I

50. GRAVITY! • Earth’s gravitational force is large because it has an enormous mass. • Anytime you lift a part of your body or lift an object, you are applying a force to overcome Earth’s gravitational force.