1 / 25

Friday

Friday. What are we going to do?. Record data for 2 runs more than minimum block length Conversions Homework! Review Homework Handout #1 Motion Detectors. Main point. How to accurately describe the motion of objects. MPV’s.

Télécharger la présentation

Friday

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Friday

  2. What are we going to do? • Record data for 2 runs more than minimum block length • Conversions • Homework! • Review • Homework Handout #1 • Motion Detectors

  3. Main point • How to accurately describe the motion of objects

  4. MPV’s • I will be recording data to see who has moved their car past the minimum distance twice • Get your papers out, complete all calculations • Task two job

  5. Task 2 (Due Wednesday) • The results must by typed or printed on an index card (3x5 or 4x6) in a table that includes: • For each run: overall displacement/ distance/ time/ velocity • The correct unit value for each number • The mean of the 3 velocity times • Discuss at least 2 specific reasons why the values may not be absolutely correct (sources of error) A drawing or photo of the car used to gather evidence is to be attached to the other side of the index card

  6. Conversions • If you are converting to a smaller unit, multiply the measurement to get a bigger number. • If you are converting to a larger unit, divide the measurement to get a smaller number

  7. Conversion Factors we use : • 1 meter = 100 centimeters • 1 meter = 1000 millimeters • 1 kilometer = 1000 meters • Interchange meter for, seconds, grams, Newtons, Joules…

  8. Time conversions • 1 minute = 60 seconds • 1 hour = 60 minutes • 1 day = 24 hours • 1 year = 365 days (approximation)

  9. Example problem • Convert 1.85 meters into centimeters • Since meters are larger than centimeters, we are converting to a smaller unit • We multiply 1.85 by the converting factor (100) = 185 cm

  10. Mathematically: • 1.85 m x 100 cm = 185 cm 1 m

  11. Example, you try: • Convert 645 seconds into the same number of minutes

  12. Answer • Since we are converting to a larger unit, we divide by factor • 645 sec / 60 = 10.75 min

  13. Another way to do the solution • Dividing is the same as multiplying by the inverse • 645 / 60 = 645 x 1/60 • 645 sec x 1 min/ 60 sec = 10.75 min

  14. Try these • 456.3 mm (millimeters) = _____ m • 456.3 /1000 = .4563 m • 8 days = ______ min • 8 x (24) x (60) = 11520 min

  15. Page 17 • Write 550 millimeters as meters • Convert to bigger, divide • 550/1000 = .550 m • Write 3.5 seconds as milliseconds • Convert to smaller, multiply • 3.5 x 1000 = 3500 millseconds

  16. Average velocity • Displacement / time • Units are m/s • V = d / t

  17. Book Problems • Find the velocity in m/s of a swimmer who swims 110 m toward the shore in 72 s • Answer v = d/t = 110 m/ 72 s = 1.5 m/s

  18. Problem 2 • Find the velocity in m/s of a baseball thrown 38 m from third base to first base in 1.7s. • Answer v = d/t = 38 / 1.7 = 22 m/s

  19. Problem 3 • Calculate the displacement in meters a cyclist would travel in 5.00 h at an average velocity of 12.0 km/h to the southwest. • Answer: • Rearrange equation v = d/t to d = vt • D = vt = 12.0 km/h x 5.00 h = 60 km • Convert 60 km into meters • Convert to smaller units means multiply • 60 km (1000 m/1 km) = 60,000 m

  20. Manipulating equations • V = d / t • Vt = dt / t t’s cancel on right • Vt = d same as d = vt

  21. Ex: problems • A) How long will it take you to travel a length 307 m at 6.4 m/s? • Ans: v = d/t 6.4 = 307 /t t =307/6.4 = 48s • If a car travels 150 blocks in 34.3 seconds, what is it’s average velocity in m/s. • Ans: convert blocks to meters- 150 x .305 = 45.8m • Then calc. vel. 45.8m /34.3s = 1.34 m/s

  22. Try this • If you can go 30 meters in 2.0 second, what is your average velocity in m/s? • Answer: 30/2 = 15 m/s • What is your average velocity in km/h? • Ans: to convert to km, you divide 30 by 1000 = .03 • to convert to hours, you divide 2 by 3600 = .000555 • Divide .03/ .000555 = 54.05

  23. Or • To convert from m/s to km/h multiply by 3.6 • To convert from km/h to m/s divide by 3.6

  24. Due Monday • Homework Handout #1 • You should get a copy from me in class • There is a copy on website

  25. Motion Detectors • Gather much more information on motion during any given time period • Uses sound to measure position • Produces a visual report on motion information ( A graph)

More Related