1. CHAPTER 5 NOTES KONICHEK

2. I. Dynamics- why objects move the way they do, A.. kinematics studied how objects move A.. kinematics studied how objects move 1. Isaac Newton- First to study the causes of accelerations 1. Isaac Newton- First to study the causes of accelerations a. summarized them in 3 laws of motion a. summarized them in 3 laws of motion

3. Welcome to the concept of universal forces

4.  II.Force- a push or pull  A. 4 types of forces  1. Gravitational- the force of attraction between all objects  a. weakest of the 4 forces  b. carried by the graviton  1. only become significant with large amounts of mass.

5. 2. Electromagnetic forces- the forces caused by the charges between particles- a. carried by the photon b. produced by the motion of charged particles. The magnetic field and the electric field vibrate at 90 to each other. 1. act as a single force- electromagnetic force

6. ► 3. Strong nuclear- this is the force which hold the nucleus together ► a. strongest of the 4 forces- 100 times stronger ► b. acts for very short distances ► 4. Weak force-a form of EM forces ► a. decay of some types of nuclei

7.  B. Grand unified theory- at some point in time all 4 forces acted as a single unified force  1. Planck time 10 -43 this is the conditions which may explain the big bang  a, all know physics breakdown at this point

8. Isaac and his 3 laws

9. III.Newtons Laws of Motion( Galileo based) III.Newtons Laws of Motion( Galileo based) A. First law- an Object with no force acting on it moves with a constant velocity. A. First law- an Object with no force acting on it moves with a constant velocity. 1. unbalanced forces- This is a force which causes motion to occur. 1. unbalanced forces- This is a force which causes motion to occur. 2. Balanced forces- equilibrium- the sum of all the forces acting on an object is zero 2. Balanced forces- equilibrium- the sum of all the forces acting on an object is zero 3. Must assign signs to show the direction of the force 3. Must assign signs to show the direction of the force a. positive forces to the right a. positive forces to the right b. negative forces to the left b. negative forces to the left 4. To find the net force it is the summation of all the forces acting on the object. 4. To find the net force it is the summation of all the forces acting on the object. a. if the net force is zero the velocity is zero and no motion results. a. if the net force is zero the velocity is zero and no motion results. 5. Expanding the first law- an Object with no net force acting on it remains at rest or moves with a constant velocity in a straight line. 5. Expanding the first law- an Object with no net force acting on it remains at rest or moves with a constant velocity in a straight line.

10. EXAMPLE OF FIRST LAW POOR LITTLE TEST TUBE

11. Mr. Konichek testing the First Law. wow man!

12. B. Second Law- The acceleration of a body is directly proportional to the net force and inversely proportional to its mass 1. F=ma 2. as force increases acceleration must increase 3. as mass increases and force is constant the acceleration must decrease 4. The net force on an object causes an acceleration 5. unit for force- 1 Kgm/s 2 = 1 Newton( N)

13. HEY- 2 ND LAW EXAMPLES

14.  C. Sample problems  1. what is the net force of an object accelerating at 5m/s2 and has a mass of 500Kg?  2. What is the acceleration of a 3000Kg truck which has a force of 8000N applied to it?

15.  D. Finding force when acceleration must be calculated, given the final velocity, and distance,  1.initial velocity is zero( Impulse force)  a. Use V f 2 = V i 2 + 2ad, solve for a:  a= V f 2 -V i 2 / 2d  substitute into F=Ma  F= M(V f 2 –V i 2 )/2d

16. PRACTICE, PRACTICE 1. example - a cannon ball with a mass of 60Kg is fired from a cannon at a velocity of 70m/s. the cannon is 2.5m long, assuming the force and acceleration are constant. What would be the force on the cannon ball while it is in the barrel of the cannon? 1. example - a cannon ball with a mass of 60Kg is fired from a cannon at a velocity of 70m/s. the cannon is 2.5m long, assuming the force and acceleration are constant. What would be the force on the cannon ball while it is in the barrel of the cannon? ASSIGNMENT- PAGE 92 1-4 ASSIGNMENT- PAGE 92 1-4

17. ► E. Third Law of Motion- For each action force there is an opposite and equal reaction force. ► 1. walking, rocket blasting off. ► 2. only the force exerted on the object will cause an acceleration.

18. Kick of a gun

19. IV. Using Newton's Laws A. Mass and weight- 1. mass- the quantity of matter 2. weight- The gravitational force exerted by a large body a. w=mg b. On earth. 1kg9.8m/s2= 1 Newton

20. B. Types of masses 1. Inertial mass- The ratio of the net force exerted on an object and it’s acceleration 1. Inertial mass- The ratio of the net force exerted on an object and it’s acceleration a. M i = F/a a. M i = F/a 2. Comparison method- Compare the mass of unknown quantity to one of known quantity on a balance. 2. Comparison method- Compare the mass of unknown quantity to one of known quantity on a balance. a. When the pans balance the masses are equal. a. When the pans balance the masses are equal.

21.  C. Friction- This is the force between two surfaces which are in contact with each other.  1. Causes- all surfaces are rough, when they rub against each other there is a weak electromagnetic bond set up between the surfaces  2. Static Friction- This is the force which opposes the start of motion  a. Have the maximum values of frictional forces  b. Must overcome the static friction when moving something.

22. 3. Sliding friction-The force between sliding surfaces 3. Sliding friction-The force between sliding surfaces a. Less that the static friction a. Less that the static friction 4. Force of friction( assignment P 99- 9 and 10) 4. Force of friction( assignment P 99- 9 and 10) a. depends upon the force pushing the surfaces together and the nature of the surfaces in contact. a. depends upon the force pushing the surfaces together and the nature of the surfaces in contact. 1. F f = MuFn (F=μF n ) 1. F f = MuFn (F=μF n ) a. μ(Mu)= coefficient of friction a. μ(Mu)= coefficient of friction b. F n = Normal force- perpendicular to the line of motion b. F n = Normal force- perpendicular to the line of motion 1. It’s the sum of all the downward forces on the object. 1. It’s the sum of all the downward forces on the object. b. We will assume the coefficient of sliding friction is independent of the surface area and velocity. b. We will assume the coefficient of sliding friction is independent of the surface area and velocity.

23. ► D. The net force causes acceleration ► 1. The acceleration of an object is the result of the net force acting on the object. ► 2. The net force is the vector sum of the applied force and the frictional force ► a) F net = F applied + F friction ► b) F net =F ground + weight ► c) throwing up the stone F n = F object + Weight

24. FREE FALL- E. The fall of bodies in air E. The fall of bodies in air 1. In a vacuum all objects accelerate at the same rate 1. In a vacuum all objects accelerate at the same rate 2. In the atmosphere objects will fall at different rates because of air resistance 2. In the atmosphere objects will fall at different rates because of air resistance a. drag- The force of the atmosphere against a moving object- form of friction a. drag- The force of the atmosphere against a moving object- form of friction 3. depends on: 3. depends on: a. size, shape, the air density, and the speed of motion. a. size, shape, the air density, and the speed of motion.

25. F. Universal Gravitation- all objects with mass attracts themselves directly proportional to the masses and inversely proportional to the square of the distance. F. Universal Gravitation- all objects with mass attracts themselves directly proportional to the masses and inversely proportional to the square of the distance. 1) F= Gm 1 m 1 /R 2 1) F= Gm 1 m 1 /R 2 2) G=6.67x10 -11 Nm 2 /kg 2 2) G=6.67x10 -11 Nm 2 /kg 2

26. 4. Falling objects gravity is pulling harder than the drag a. as the velocity of the object increases the drag increases until the drag force equals the pull of gravity... net force is zero 1. the object stops accelerating... terminal velocity 2. a falling parachutist spread eagle falls about 60m/s 3. with the chute open 5m/s. PRACTICE PROBLEMS ASSIGNMENT PAGE 105 :1, P106 :4,6,8,9,10, 12,15,p 107- 22,24