Presentation is loading. Please wait.

Presentation is loading. Please wait.

Chapter 11 Motion You will need a calculator for this chapter!

Similar presentations


Presentation on theme: "Chapter 11 Motion You will need a calculator for this chapter!"— Presentation transcript:

1 Chapter 11 Motion You will need a calculator for this chapter!

2 Section 11.1 Distance and Displacement p. 328

3 What is a frame of reference?
How fast was the boat traveling? Relative to what? Motion must be described relative to a frame of reference relative motion Relative to Earth’s surface (understood)

4 How fast was the boat traveling?
Relative to spectators? Really Fast!!!! Relative to driver? ZERO! Driver & boat…same frame of reference Tennis ball ex…(p.329) Einstein’s Theory of Relativity – 10:06

5 Choosing a Frame of Reference
Conclusion?? The Frame of Reference determines how motion of an object is described.

6 Measuring Distance Distance - length btwn 2 pts SI unit….meter (m)
Derived units cm (snail crawling) km (distance btwn 2 cities)

7 Measuring Displacements
distance v.s. displacement? “walk 5 blocks” (distance ) “walk 5 blocks north from the bus stop” (displacement) – direction & distance from start to end Displacement needed for accurate directions

8 Combining Displacements
Vector? Measurement w/ magnitude and direction Magnitude? Size, length, amount Described w/

9 Displacement along a straight line
2 vectors… same direction Add magnitudes Ex. A car travels 10 km north, stops to refuel, then travels 20 km north total distance = 30 km total displacement = 30 km (10 km north + 20 km north) from starting pt

10 Displacement along a straight line
2 vectors…. opposite directions Subtract mags Ex. Bicyclist travels 5 km east, turns around and travels 3 km west Bicyclists total distance = 8 km total displacement = 2 km east (5 km – 3 km)

11 Displacement That isn’t along a straight path
2+ vectors w/ different directions Combine by graphing Resultant vector - sum of all vectors Shows distance & displacement related but different

12 Section 11.1 Assessment What is a frame of reference? How is it used to measure motion? How are distance and displacement similar and different? How are displacements combined? A girl who is watching a plane fly tells her friend that the plane isn’t moving at all. Describe a frame of reference in which the girl’s description would be true.

13 Section 11.1 Assessment Should your directions to a friend for traveling from one city to another include displacements or distances? Explain your choice. A spider is crawling on a wall. First it crawls 1 m up, then 1 m to the left, and then 1 m down. What is the distance the spider crawled? What is the spider’s displacement?

14 Section 11.2 Speed and Velocity p. 332
Have your calculator on your desk

15 Can you describe the speed of the skaters?
Video Can you describe the speed of the skaters? What information is needed to determine the speed of the skaters? Speed - ratio of distance traveled to time needed to travel that distance. SI unit meters per second (m/s) derived units: km/hr cm/s

16 v = d t Average speed entire duration of a trip,
average speed - total distance traveled (d), divided by total time (t) Average Speed = total distance total time Or….. v = d t Calculating average speed Math Skills p. 333

17 Average Speed ( v ) Avg speed doesn’t reflect most common speed of trip stops, curves, hills Useful – tells how long trip will take If v is 60 mi/hr & destination is 120 mi, your TOA is 2 hours Calculating average speed Math Practice p. 333

18 Instantaneous speed Instantaneous speed (v) - rate object is moving at given moment speedometers show instantaneous speed 100 mi/hr (160 km/hr)

19 Graphing Motion Distance-time graph Slope = change in vertical axis
change in horizontal axis Slope is speed of object plotted

20 Graphing Motion Slope (rise/run) = speed Calculate: What can you
conclude about the speed of the RC car? Distance v.s. Time of an RC car

21 Graphing Motion Distance-time graph 4 segments (A-D) to find average speed for each segment Calculate: Describe the speed of the car in segment B? Driving speed of a car in rush hour traffic D C B A

22 Velocity Pilots and control tower communicate describing velocity of
planes Velocity describes speed and direction vector v changes if speed, direction, or both change

23 Velocity Car traveling at constant speed (55 mi/hr)
How would you describe its velocity? Direction changing on circular track, velocity changing

24 Changing Velocities When velocities in same direction, add together
River velocity= 7km/hr east Boat velocity= 16km/hr east Calculate: 16 km/hr east 7 km/hr east

25 Changing Velocities a2 + b2 = c2
When velocities at rt angles, use Pythagorean theorem to solve plane= 400km/hr west wind speed= 25km/hr south a2 + b2 = c2 Calculate: 400 km/hr west 25 km/hr south Science of NHL hockey – vectors 4:29

26 Section 11.2 Assessment You and a friend are watching a baseball game on ESPN where the commentator says “the pitcher’s velocity of 100 mi/hr is virtually unhittable”. Your friend agrees. What do you think? What does the slope on a distance-time graph indicate?

27 Section 11.2 Assessment Does a car’s speedometer show instantaneous speed, average speed, or velocity? Explain. An Olympic swimmer swims 50.0 meters in 23.1 seconds. What is his average speed?

28 Section 11.2 Assessment A plane’s average speed between two cities is 600 km/hr. If the trip takes 2.5 hours, how far does the plane fly?

29 Section 11.2 Assessment A discus thrower threw his disc 139 meters through the air. While in flight, the disk traveled at an average speed of 13.0 m/s. How much time did the disk remain in the air?

30 Section 11.3 Acceleration p. 342
Have your calculator on your desk Suzuki Hayabusa

31 What is acceleration? Remember velocity is speed w/ direction
Acceleration - rate velocity changes Vector What is a rate? it takes time

32 Changes in speed green stoplight car moves forward
acceleration (positive change in car’s speed) pushes you back in seat red stoplight  speed decreases (negative change) you fall forward towards dash vectors_car_velocity_accel.notebook

33 Free-Fall Free-fall - acceleration toward Earth b/c gravity
Speed/velocity SI units is m/s Units for acceleration - meters per second per second or m/s2 The 2nd “second” is time needed to change speed (rate)

34 a near Earth = 9.8 m/s2 Free-Fall 29.4 m/s after 3 seconds
bungee jumper will accelerate 9.8 meters per second every second he’s in FF 1 s of FF speed = 9.8 m/s 2 s of FF speed =19.6 m/s (sped up 9.8 m/s in 1 s) What is speed after 3 s? 29.4 m/s after 3 seconds

35 If the Earth is moving, why can I not feel it?
body detects changes in speed Earth spin constant speed 850 mi/hr at mid latitudes (faster at equator) Revolves 67,000 mi/hr 2x bullet speed! 1.6 million miles / day! WOW!!!

36 a occurs if direction changes even if speed constant
Changes in Direction a occurs if direction changes even if speed constant Ferris wheel & carousel = constant speed accelerate b/c change direction

37 Changes in speed and direction
roller coasters winding roads

38 Constant Acceleration
straight line motion & speeding up / slowing down - constant acceleration v of object changes same amt each sec Indy car pulling G’s 3:00

39 Calculating Acceleration
calculate acceleration for straight-line motion using this equation: Acceleration = change in velocity total time or….. (vf – vi) t (vf – vi) Velocity and acceleration 1:58 a x t venn diagram review.notebook

40

41 Math Practice #1 p. 346 A car traveling at 10 m/s starts to decelerate steadily. It comes to a complete stop in 20 seconds. What is its acceleration?

42 Math Practice #2 p. 346 An airplane travels down a runway for 4.0 seconds with an acceleration of 9.0 m/s2. What is its change in velocity during this time?

43 Math Practice #3 p. 346 A child drops a ball from a bridge. The ball strikes the water under the bridge 2.0 seconds later. What is the velocity of the ball when it strikes the water?

44 Math Practice #4 p. 346 A boy throws a rock straight up into the air. It reaches the highest point of its flight after 2.5 seconds. How fast was the rock going when it left the boy’s hand? (acceleration is downward b/c of gravity, but velocity is upward)

45 Acceleration of a Mercedes-Benz
Volunteer timers – we will average the times How much time does it take to go from 0 km/hr to 200 km/hr?

46 Graphs of Accelerated motion
Speed-time graph displays acceleration Slope of speed-time graph is acceleration of object

47

48 Distance-Time Graphs Accelerated motion is represented by a curved (non-linear) line on distance-time graph Slope (speed) greater after 3 sec than 1 sec acceleration video 3:24

49 Instantaneous Acceleration
Instantaneous acceleration (IA) - how fast velo changing at specific instant Skateboarder continually changes speed & direction his IA always changing

50 Instantaneous Acceleration
Vector of skateboarder’s acceleration can point any direction Vector length represents how fast velocity is changing IA even if standing still and acceleration vector zero

51 Section 11.3 Assessment Describe 3 types of changes in velocity.
What is the equation for acceleration? What does the slope on a speed-time graph show? Define instantaneous acceleration.


Download ppt "Chapter 11 Motion You will need a calculator for this chapter!"

Similar presentations


Ads by Google