Presentation on theme: "Chapter 2a Motion 2-1. Speed 2-2. Vectors 2-9. Second Law of Motion"— Presentation transcript:
1 Chapter 2a Motion 2-1. Speed 2-2. Vectors 2-9. Second Law of Motion 2-3. Acceleration2-4. Distance, Time, and Acceleration2-5. Free Fall System2-6. Air Resistance2-8. Mass2-9. Second Law of Motion2-10. Mass and Weight2-11. Third Law of Motion2-12. Circular Motion2-13. Newton's Law of Gravity2-14. Artificial Satellites
2 2-1. Speed Definitions: v = d/t Speed General formula for speed: The rate at which something moves a given distance.Faster speeds = greater distancesGeneral formula for speed:Speed = distance / timeAbbreviations commonly used:d = distance t = time v = speedv = d/t
10 Super Slinky Experiment 2-5. Free FallThe acceleration of gravity (g) for objects in free fall at the earth's surface is 9.8 m/s2.Galileo found that all things fall at the same rate.The Slinky ExperimentSuper Slinky Experiment
11 2-5. Free Fall The rate of falling increases by 9.8 m/s every second. Height = ½ gt2For example:½ (9.8 )12 = 4.9 m ½(9.8)22 = 19.6 m½ (9.8)32 = 44.1 m½ (9.8)42 = 78.4 m
12 2-5. Free FallA ball thrown horizontally will fall at the same rate as a ball dropped directly.
13 2-5. Free FallA ball thrown into the air will slow down, stop, and then begin to fall with the acceleration due to gravity. When it passes the thrower, it will be traveling at the same rate at which it was thrown.
14 2-6. Air Resistance Ideal angle for a projectile In a vacuum, maximum distance is at an angle of 45oWith air resistance (real world), angle is lessBaseball will go furthest hit at an angle of around 40o
15 2-5. Free FallAn object thrown upward at an angle to the ground follows a curved path called a parabola.
16 2-6. Air Resistance In air… In a vacuum A stone falls faster than a featherAir resistance affects stone lessIn a vacuumA stone and a feather will fall at the same speed.
17 2-6. Air Resistance Free Fall A person in free fall reaches a terminal velocity of around 54 m/sWith a parachute, terminal velocity is only 6.3 m/sAllows a safe landing
18 2-7. First Law of MotionThe first law of motion states: If no net force acts on it, an object at rest remains at rest and an object in motion remains in motion at a constant velocity.
19 Foucault PendulumInertia keeps a pendulum swinging in the same direction regardless of the motion of the earth. This can be used to measure the motion of the earth. As the Foucault Pendulum swings it appears to be rotating, but it is the earth that is rotating under it. To the right is the Foucault Pendulum at the Pantheon in Paris, France.
20 Other Web sites that illustrate the Foucault Pendulum.
21 2-8. MassInertia is the apparent resistance an object offers to any change in its state of rest or motion.Balloon in car viedo
22 2-9. Second Law of Motion F = Ma Newton's second law of motion states: The net force on an object equals the product of the mass and the acceleration of the object. The direction of the force is the same as that of the acceleration.F = Ma
23 2-9. Second Law of MotionA force is any influence that can cause an object to be accelerated.The pound (lb) is the unit of force in the British system of measurement:1 lb = 4.45 N (1 N = lb)
24 2-10. Mass and Weight Weight Definition: The force with which an object is attracted by the earth’s gravitational pullExample: A person weighing 160 lbs is being pulled towards the earth with a force of 160 lbs (712 N).Near the earth’s surface, weight and mass are essentially the same
25 2-11. Third Law of MotionThe third law of motion states: When one object exerts a force on a second object, the second object exerts an equal force in the opposite direction on the first object.
26 2-11. Third Law of MotionExamples of the 3rd Law
27 2-12. Circular MotionCentripetal force is the inward force exerted on an object to keep it moving in a curved path.Centrifugal force is the outward force exerted on the object that makes it want to fly off into space.