c2 motion

Chapter 2a Motion2-1. Speed 2-2. Vectors2-3. Acceleration2-4. Distance, Time, and Acceleration 2-5. Free Fall System2-6. Air Resistance2-8. Mass

2-9. Second Law of Motion2-10. Mass and Weight2-11. Third Law of Motion 2-12. Circular Motion2-13. Newton's Law of Gravity2-14. Artificial Satellites

2-1. SpeedDefinitions:SpeedThe 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

2-1. SpeedVelocityDistanceTime

2-1. SpeedAverage speed is the total distance traveled by an object divided by the time taken to travel that distance. Instantaneous speed is an object's speed at a given instant of time.

2-2. VectorsMagnitude of a quantity tells how large the quantity is.Scalar quantities have magnitude only.Vector quantities have both magnitude and direction.

2-2. VectorsVelocity is a vector quantity that includes both speed and direction.

2-3. AccelerationAcceleration of an object is the rate of change of its velocity and is a vector quantity. For straight-line motion, average acceleration is the rate of change of speed:

2-3. Acceleration3 Types of AcceleartionSpeeding Up

Slowing Down Turning

2- 4. Distance, Time and Acceleration (V1 + V2) Vavg = 2d = vavg t d = at2

(20mph + 60mph) = 40mph 230mph 2hr = 60miles 10m/s/s 52 = 125m

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

2-5. Free FallThe rate of falling increases by 9.8 m/s every second.Height = gt2For example: (9.8 )12 = 4.9 m (9.8)22 = 19.6 m (9.8)32 = 44.1 m (9.8)42 = 78.4 m

2-5. Free FallA ball thrown horizontally will fall at the same rate as a ball dropped directly.

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.

2-6. Air ResistanceIdeal angle for a projectileIn 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

2-5. Free FallAn object thrown upward at an angle to the ground follows a curved path called a parabola.

2-6. Air ResistanceIn airA stone falls faster than a featherAir resistance affects stone lessIn a vacuumA stone and a feather will fall at the same speed.

2-6. Air ResistanceFree FallA 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

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.

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.

Foucault PendulumOther Web sites that illustrate the Foucault Pendulum.http://en.wikipedia.org/wiki/File:Foucault-rotz.gifhttp://www.physclips.unsw.edu.au/jw/foucault_pendulum.htmlhttp://aspire.cosmic-ray.org/labs/scientific_method/pendulum.swfhttp://www.calacademy.org/products/pendulum/page7.htmhttp://www.youtube.com/watch?v=nB2SXLYwKkM

2-8. MassInertia is the apparent resistance an object offers to any change in its state of rest or motion. Balloon in car viedo

2-9. Second Law of MotionNewton'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

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 = 0.225 lb)

2-10. Mass and Weight WeightDefinition: The force with which an object is attracted by the earths gravitational pullExample: A person weighing 160 lbs is being pulled towards the earth with a force of 160 lbs (712 N).Near the earths surface, weight and mass are essentially the same

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.

2-11. Third Law of MotionExamples of the 3rd Law

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.

2-12. Circular Motion

2-12. Circular Motion833 N is needed to make this turn.If he goes too fast, which wheels are likely to come off the ground first?

2-12. Circular Motionhttp://www.youtube.com/watch?v=84L5uXOyVhwhttp://www.youtube.com/watch?v=TGHvFpNCrtQhttp://www.youtube.com/watch?v=6NAZtd-qHSQhttp://www.youtube.com/watch?v=A0H7TYzcMaY

2-13. Newton's Law of Gravity G = 6.67 x 10-11 Nm/kg2

2-13. Newton's Law of Gravity How can we determine the mass of the earth using an apple?This illustrates the way scientists can use indirect methods to perform seemingly impossible tasks

2-13. Newton's Law of Gravity How can we determine the mass of the earth using an apple?This illustrates the way scientists can use indirect methods to perform seemingly impossible tasks= mg

2-15. Artificial SatellitesThe world's first artificial satellite was Sputnik I, launched in 1957 by the Soviet Union. GPS-Global Positioning Satellite

2-15. Artificial SatellitesThe escape speed is the speed required by an object to leave the gravitational influence of an astronomical body; for earth this speed is about 40,000 km/h.

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