10km/h it has more momentum

1. 10km/h it has more momentum

2. What does it mean to have momentum? • Use momentum in a sentence. When is it commonly used? • What does it mean in that context? • How does the common use relate to the science use?

3. What does it mean to have momentum? • Talk to your partner: • Use momentum in a sentence. When is it commonly used? • What does it mean in that context? • How does the common use relate to the science use?

4. Momentum • Momentum is a commonly used term in sports. A team that has the momentum is on the move and is going to take some effort to stop. • Momentum is a physics term; it refers to the amount of motion that an object has. • A sports team that is on the move has the momentum. • If an object is in motion (on the move) then it has momentum.

5. Predict, Observe, Explain • Which will hit the floor faster? • Which hit the floor first? • Why did this happen? What affects the rate at which an object falls? 16.2g aluminum 53.58g copper

6. Momentum Defined • Momentum is defined as "mass in motion." • All objects have mass; so if an object is moving, then it has momentum • The amount of momentum that an object has depends upon two things • Mass (how much stuff there is) • Velocity (how fast the stuff is moving) • Momentum depends upon the variables mass and velocity. • The formula is: P=mv (p is momentum)

7. Momentum’s Units P=m•v • The units for momentum would be mass units times velocity units. • The standard metric unit of momentum is the kg•m/s. • Other units that are acceptable (though not conventional) include kg•km/hr, and g•cm/s. • To find your momentum units, use the units from your equation.

8. Find the unit P=m•v • A 2,000kg car travels 3m/s • kg*m/s • A 4g ball rolls .2km/h • g*km/h • A 333,000kg jet travels 885km/h • kg*km/h

9. Speed Measuring motion

10. Calculating Speed • Speed (S) = distance traveled (d) / the amount of time it took (t). • Formula: S = d/t

11. Units for speed • Variable, but will always be a distance unit / a time unit • Ex. Cars: km/h • Jets: km/h • Snails: cm/s • Falling objects: m/s

12. Calculating speed S = d/t • If I travel 100 kilometers in one hour then I have a speed of… • 100 km/h • If I travel 1 meter in 1 second then I have a speed of…. • 1 m/s

13. Average speed • Average Speed is usually NOTCONSTANT • Ex. Cars stop and go regularly • Ex. Runners go slower uphill than downhill • Average speed= total distance traveled/total time it took.

14. Calculating Average Speed • It took me 1 hour to go 40 km on the highway. Then it took me 2 more hours to go 20 km using the streets. • Total Distance: • 40 km + 20 km = 60 km • Total Time: • 1 h + 2 h = 3 hr • Ave. Speed: • total d/total t = 60 km/3 h = 20 km/h

15. Question • I ran 1000 m in 3 minutes. Then ran another 1000 m uphill in 7 minutes. What is my average speed? • A) 100 m/min • B) 2000 m/min • C) 10 m/min • D) 200 m/min • E) 20 m/min Total Dist. = 1000 m + 1000 m = 2000 m Total Time = 3 min + 7 min = 10 min Ave speed = total dist/total time = 2000m/10 min = 200 m/min = D

16. Velocity • Velocity – the SPEED and DIRECTION of an object. • Example: • An airplane moving North at 855 km/h • A missile moving towards you at 200 m/s

17. Question • What is the difference between speed and velocity? • Speed is just distance/time. Velocity includes direction as well.

18. But… • In this class we will pretty much use them interchangeably. • Just know there’s a difference

19. Graphing Speed: Distance vs. Time Graphs Denver Phoenix

20. Graphing Speed: Distance vs. Time Graphs Speed = Slope = Rise/Run Rise

21. Graphing Speed: Distance vs. Time Graphs Speed = Slope = Rise/Run Rise=? 600 km 3 h

22. Graphing Speed: Distance vs. Time Graphs Speed = Slope = Rise/Run Rise=? 600 m 3 hours Rise/Run = 600 km/3 hr = 200 km/hr

23. Different Slopes Slope = Rise/Run = 0 km/1 hr = 0 km/hr Rise = 2 km Run = 1 hr Rise = 0 km Run = 1 hr Slope = Rise/Run = 2 km/1 hr = 2 km/hr Rise = 1 km Run = 1 hr Slope = Rise/Run = 1 km/1 hr = 1 km/hr

24. Question Average Speed = Total distance/Total time = 12 km/6 hr = 2 km/hr Measure by Slope first to last data point • Below is a distance vs. time graph of my position during a race. What was my AVERAGE speed for the entire race? Rise = 12 km Run = 6 hr

25. Question • What does the slope of a distance vs. time graph show you about the motion of an object? • It tells you the SPEED

26. Question • Below is a distance vs. time graph for 3 runners. Who is the fastest? Leroy is the fastest. He completed the race in 3 hours

27. What happened here? Distance goes down? What’s that mean?

28. Distance goes down?

29. To go to A.T. • Math practice done and assignment turned in

30. Exit Question • What is the difference between velocity and speed?

31. Your turn • Practice the math on the back of your worksheet • Get a computer and finish packet from last week • Vocab – make sure you research the PHYSICS meaning, and write the definition in your own words. Note where you found the definition. GOOGLE IS NOT A SOURCE. • To go to A.T. have at least the vocab for this weeks quiz done • Acceleration • Momentum • Velocity • Force Add to list

32. Acceleration

33. Acceleration • Acceleration = speeding up • Acceleration – the rate at which velocity changes • Can be an: • Increase in speed • Decrease in speed • Change in direction

34. Types of acceleration • Increasing speed • Example: Car speeds up at green light • Decreasing speed • Example: Car slows down at stop light • Changing Direction • Example: Car takes turn (can be at constant speed) screeeeech

35. Question • How can a car be accelerating if its speed is a constant 65 km/h? • If it is changing directions it is accelerating

36. Calculating Acceleration • If an object is moving in a straight line • Units of acceleration: • m/s2 Acceleration is simply expressed as velocity per seconds. And Velocity as meter per seconds. So the SI notation is m*s*s.

37. Calculating Acceleration Final Initial 1 s 2 s 3 s 4 s 0 s 4 m/s 12 m/s 16 m/s 0 m/s 8 m/s

38. Question • A skydiver accelerates from 20 m/s to 40 m/s in 2 seconds. What is the skydiver’s average acceleration?

39. Graphing Acceleration • Can use 2 kinds of graphs • Speed vs. time • Distance vs. time

40. Graphing Acceleration:Speed vs. Time Graphs • Speed is increasing with time = accelerating • Line is straight = acceleration is constant

41. Graphing Acceleration:Speed vs. Time Graphs Rise = 4 m/s Run = 2 s • In Speed vs. Time graphs: Acceleration = Rise/Run = 4 m/s ÷ 2 s = 2 m/s2

42. Graphing Acceleration:Distance vs. Time Graphs • On Distance vs. Time graphs a curved line means the object is accelerating. • Curved line also means your speed is increasing. Remember slope = speed.

43. Question Run = 3 s Rise = -6 m/s Above is a graph showing the speed of a car over time. 1) How is the speed of the car changing (speeding up, Slowing down, or staying the same)? 2) What is this car’s acceleration? • The car is slowing down • Acceleration = rise/run = -6m/s ÷3s = -2 m/s2

44. Positive acceleration Negative acceleration

45. Question: The black and red lines represent a objects that are accelerating. Black is going a greater distance each second, so it must be speeding up. Red is going less each second, so must be slowing down Remember: in distance vs. time graphs: curved line = accelerating, flat line = constant speed • Which line represents an object that is accelerating?

46. Question: Hard one Above is a graph showing the speed of a car over time. 1)What would a distance vs. time graph for this look like?