Velocity Vectors

1
Velocity Vectors
Louisiana Tech University
Technology-Rich Transportation Engineering
Experiences
2
Activity 1

• Background
• Practice using technology
• Collect data
• -gt Lunch
• Analyze data

3
Learning Objectives/Standards

• CCSS.Math.Content.HSN.VM.A.1() Recognize vector
  quantities as having both magnitude and
  direction. Represent vector quantities by
  directed line segments, and use appropriate
  symbols for vectors and their magnitudes (e.g.,
  v, v, v, v).
• CCSS.Math.Content.HSN.VM.A.3() Solve problems
  involving velocity and other quantities that can
  be represented by vectors.
• CCSS.Math.Content.HSG.SRT.C.8Use trigonometric
  ratios and the Pythagorean Theorem to solve right
  triangles in applied problems.
• CCSS.Math.Content.HSG.SRT.D.11() Understand and
  apply the Law of Sines and the Law of Cosines to
  find unknown measurements in right and non-right
  triangles (e.g., surveying problems, resultant
  forces).

4
Problem Statement

• Transportation engineers often need to measure
  the speed with which people drive on a particular
  segment of road.
• Radar guns can be used for this purpose, but they
  only measure the speed at which a car approaches
  the gun.
• How can a transportation engineer safely
  determine the true speed?

5
Background

• Radar uses the change in frequency of the radio
  pulse that bounces back (Doppler effect).

Brain, Marshall.  "How Radar Works"  01 April
2000.  HowStuffWorks.com. lthttp//science.howstuff
works.com/radar.htmgt  07 July 2015.
6
You will need

• Radar guns
• Measuring tape
• A non-busy road
• Sidewalk chalk or flag markers
• A driver and vehicle

7
Get your radar gun ready

• Load batteries
• Practice switching between MPH and KPH
• See how fast you can run/throw

8
Identify your driver and route
9
Well use a 10 x 10 grid to choose positions -

• Once we get out there, make sure you record your
  position

10
Back Inside

• How fast was the vehicle going?
• Why did you all get different speeds?
• Is there any pattern to your answers?

11
Lets figure out the angle

• Side a ____
• Side b ____
• Angle C ____

12
Law of Cosines

• Side c _____

13
Now we can find A using Law of Sines

• Angle A ____

14
Repeat the process to find the angle you measured
from

• Side a ____
• Side b ____
• Angle C ____
• Side c _____
• Angle A ____

15
(No Transcript)
16
(No Transcript)
17
(No Transcript)
18
Discussion

• Are your answers more similar than before?
• Are they exactly the same? Why might that be?
• Whose measurements were the most accurate?
• Whose were the least accurate?
• What advice would you give someone trying to
  measure speed using a radar gun?

19
Now what velocity do you think the vehicle was
going?