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LINEAR MOTION

LINEAR MOTION. Reference Object Speed Velocity Acceleration Free Fall Motion. Motion is Relative!. Motion is compared to an object that is considered stationary- a reference object. Here, the car and the Dalmatian are in motion compared

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LINEAR MOTION

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  1. LINEAR MOTION • Reference Object • Speed • Velocity • Acceleration • Free Fall Motion

  2. Motion is Relative! Motion is compared to an object that is considered stationary- a reference object. Here, the car and the Dalmatian are in motion compared to the road, which is stationary. The road is a common reference point.

  3. Can a reference object be moving? YES! Sitting in your car for example. You are moving but objects appear to be moving as compared to your position. Cars speeding by you, or you moving past other cars, the trees and people on the sidewalk. http://www.youtube.com/watch?v=bKkarFdnVbw

  4. SPEED! How fast an object moves or changes position in relation to a reference object. Speed is the rate of motion. Speed is expressed as a unit of distance divided by a unit of time. Examples include: miles per hourmeters per second kilometers per hour centimeters per day meters per minute light years per century

  5. Instantaneous Speed - Speed at that particular instant. Constant Speed - Speed that does not change (held constant). Average Speed – calculated by taking the total distance covered divided by the total time elapsed. There may be speed changes along the way.

  6. This car is travelling along…. At any moment, the driver may look at the speedometer and read the gauge to obtain the instantaneous speed. If the driver sets his cruise control at 50 mph, then he is traveling at a constant speed of 50 mph.

  7. Jogger moving at a constant rate. What do you notice about his change in position per unit time interval?

  8. What would the graph of time vs position look like?

  9. If the car speeds up and slows down along its journey, then we can say that the car has an average speed. Say that the car travels 80 miles in 2 hours. Then, Average speed = total distance 80 miles total time elapsed 2 hours = 40 miles per hour

  10. Solving for other variables: Using the general equation, speed = distance traveled time elapsed We can solve for any of the three variables by manipulating the equation. Time = distance speed Distance = speed x time

  11. This Siamese cat is about to capture its lunch. If the cat can pounce on the mouse moving at a horizontal speed of 10 meters per second, and the mouse is 2.5 meters away, how long will it take the cat to get there?

  12. Assuming this penguin travels at a constant speed down the slope, how far will it travel in 5 minutes at a rate of 15 miles per hour?

  13. It’s time for practice!

  14. How does “Velocity” differ from “Speed?” Velocity is a vector quantity (Speed is scalar) Velocity is speed in a given direction. Velocity (v) can be determined by using the same mathematical formula for speed as long as a direction is stated along with it. This could be in the form of a direction or as a positive or negative value. Thus : Velocity = Displacement / Time elapsed Or v = df - di = Δd tf – ti Δt For example: If a truck travels north 100 miles in 2 hours, then the average velocity of the truck can be expressed as 50 mph north.

  15. Displacement • Displacement is the change in position. (It doesn’t matter how you get there) 6 miles start 2 miles finish Distance traveled is 8 miles, but the displacement is 6.3 miles!!

  16. During third hour I walked from my desk to the office to get my mail. I then returned to my desk. The distance to my mail box is 37 meters. What total distance did I walk? What was my total displacement?

  17. Displacement Vectors • Vectors are arrows that show direction and magnitude. Here the arrows are different lengths to show varying displacement. 3 miles 5 miles 10 miles

  18. Setting the standard • Positive direction – arrow to the right • Negative direction – arrow to the left UP + DOWN -

  19. Velocity Vectors are simply arrows used to represent the magnitude and direction of motion. A vector is an arrow. The length of the arrow drawn shows the size or magnitude of the velocity (speed) and the head of the arrow shows the direction of the motion. Examples: 10 mph East 30 mph East 5 mph North Note that the second arrow points in the same direction as the first arrow, but is three times longer, showing that the speed is three times faster. The third arrow is half the length of the first arrow, showing it is half the speed; it also points in a different direction. These are examples of velocity vectors.

  20. Setting the standard • A positive or negative velocity simply shows direction. (Example: Forward or reverse) • Positive velocity – arrow to the right • Negative velocity – arrow to the left UP + DOWN -

  21. Vectors on a coordinate system(angle and direction given) N W E S

  22. Vectors on a coordinate system(only angle given) N W E S

  23. For Practice:Using your protractor and ruler, draw vectors for the following velocities:Scale 1 cm = 5 m/s 1. 10 m/s South 2. 35 m/s East3. 26 m/s at 196 ْ 4. 30 m/s 40ْN of E 5. 15 m/s 20 degree S of E 6. 28 m/s 15 degrees E of N

  24. For Practice:Using your protractor and ruler, draw vectors for the following velocities:Scale 1 cm = 5 m/s 1. 10 m/s South 2. 35 m/s East3. 26 m/s at 196 ْ 4. 30 m/s 40ْNE 5. 15 m/s 20 degree S of E 6. 28 m/s 15 degrees E of N

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