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Understanding Motion

Understanding Motion. Brittany Moore 8/29/12. What is motion?. motion : movement What two things are important in describing motion: Distance Time Do you have to see something literally move to know its in motion?. Distance vs. Displacement. Distance : how far something has moved

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Understanding Motion

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  1. Understanding Motion Brittany Moore 8/29/12

  2. What is motion? • motion: movement • What two things are important in describing motion: • Distance • Time • Do you have to see something literally move to know its in motion?

  3. Distance vs. Displacement • Distance: how far something has moved • Meters (m), kilometers (km) • Displacement: distance and direction of an object’s change in position from the starting point • What are the differences between distance and displacement?

  4. Speed • Speed: distance an object travels per unit of time • How do we calculate speed? • Speed = distance/time • Ex: A car traveling at a constant speed covers a distance of 750 m in 25 s. What is the cars speed?

  5. More examples of speed • A passenger elevator travels from the first floor to the 60th floor, a distance of 210 m, in 35 s. What is the elevators speed? • A motorcycle is moving at a constant speed of 40km/h. How long does it take the motorcycle to travel a distance of 10km?

  6. Can speed change over time? • Does your car always run at a constant speed? • What might a graph of your car’s speed look like on a typical day to school?

  7. Types of Speed • Average speed: total distance traveled divided by the total time of travel • Ex: A runner travels 100 m in 30 s. What is their average speed? • Instantaneous speed: speed at a given point of time • Ex: On my way to school I look down to see that I am travelling 136.8 km!

  8. How are graphs used? • What kind of graph would be best to show motion? • Distance over an amount of time… • How does the steepness of a line effect the speed? • Speed = slope

  9. Example

  10. Yay for Outside! • Lets have a race…can you calculate your speed? • Speed = distance / time = m / s • Work in groups to complete worksheet.

  11. Velocity • Velocity: speed of an object and the direction of its motion • The velocity of an object can change even if the speed of the object stays the same • Ex: BMS—the race car has a constant speed and is going around an oval track; even though the speed remains constant, the velocity changes because the direction of the car’s motion is changing constantly

  12. Example

  13. Acceleration • Acceleration: the rate of change of velocity • Acceleration occurs when an object changes its speed, direction, or both. • Change in velocity = final velocity – initial velocity • Acceleration = Vf – Vi Units in m/s2 t • Ex: Speeding up and slowing down. • As a car speeds up: positive velocity, acceleration, and speed. • As a car brakes: positive velocity, negative acceleration (deceleration) and decreasing speed.

  14. Connections… • Don’t athletes have to make quick changes in acceleration? • Can you think of any equipment used by athletes to help with this? Yes! Examples include: -starting blocks for runners -cleats on shoes -rubber soled shoes -special clothing

  15. What is force? • Force: push or pull on an object; changes in the movement • Ex: hitting a tennis ball, gravity on your body, pool, etc. • Force = mass x acceleration

  16. Net Force • Net force: when two or more forces act on an object at the same time • Balanced: equal forces acting in opposite direction • Unbalanced: unequal forces acting in opposite direction

  17. Newton’s Laws of Motion

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