Uniform Circular Motion - PowerPoint PPT Presentation

1 / 27
About This Presentation
Title:

Uniform Circular Motion

Description:

Uniform Circular Motion U.C.M. What is UCM? Defn: Uniform Circular Motion is the motion of a body travelling at constant speed in a circular path. – PowerPoint PPT presentation

Number of Views:742
Avg rating:5.0/5.0
Slides: 28
Provided by: itc9175
Category:

less

Transcript and Presenter's Notes

Title: Uniform Circular Motion


1
Uniform Circular Motion
  • U.C.M.

2
What is UCM?
  • Defn Uniform Circular Motion is the motion of a
    body travelling at constant speed in a circular
    path.
  • Examples
  • a Merry-go-round at full speed
  • A car rounding a turn at CONSTANT speed
  • The Rotor at Cedar Point

3
Period and Frequency
  • The PERIOD of an object in UCM is the time it
    takes for one full cycleT in seconds.
  • The FREQUENCY of an object in UCM is the number
    of COMPLETE cycles in some unit of timef in
    1/s or Hertz (Hz).
  • T and F are reciprocals

4
Rotation v. Revolution
  • What is the difference between these two? Can
    you show with a picture?
  • See the following web site for help
    http//server.remc12.k12.mi.us/coldlegg/sci-dept/o
    lympiad/starry-night/rot-rev.html

5
Rotation
  • is moving around an internal axis (ie. The Earth
    upon its axis)

6
Revolution
  • Moving around an external axis (ie. The moon
    around the Earth)

7
Speed of an object in UCM
  • Recall, speed distance time Apply this to
    UCM
  • What are the units of v?

8
Examples
  • A bug sits on the outer edge of a rotating 33-1/3
    rpm record. Find the speed of the bug in m/s and
    mph if the record has a diameter of 30cm.
  • Tire Balancingsee Ex. 1 on p. 131

9
Whats constant and whats not?
  • When an object is in UCM, what remains constant,
    its SPEED or its VELOCITY???
  • Its SPEED!
  • Since the direction is always changing...

10
Centripetal Acceleration
  • If an object in UCM is constantly changing
    velocity then it must be accelerating
  • Can you describe its acceleration?
  • The acceleration is toward the center of the
    objects motion and is said to be CENTRIPETAL.

11
Centripetal FORCE
  • If an object in UCM is accelerating what is the
    force responsible for this acceleration?
  • RecallF ma

12
Determine the origin of the Centripetal Force in
each example
13
Survey says
14
Tight Turns and Gentle Turns 1
  • A 2250 kg Honda Accord is rounding a turn at 25
    mph. What force is needed to keep it on the road
    if the turning radius is 50m? If it is 100m?
    What force is responsible for this?

15
Tight Turns and Gentle Turns 2
  • How does the maximum speed with which a car can
    round a turn depend on its mass (weight) of the
    car? How fast could the car in example 1 go if µ
    0.75?

16
Centripetal vs. Centrifugal?!?
  • Put yourself in the frame of reference of a body
    in UCM. What do you feel or experience what
    is actually happening?
  • Demo The Bulging Earth?!?
  • Which force is the real McCoy? and which is an
    imagined force?

17
Airplane Turns
  • How does an airplane negotiate a turn when there
    is no friction
  • Draw a Free Body Diagram...

Lift
Weight
18
Airplane Examples
  • How fast could a 124,000kg DC-9 negotiate a turn
    of 5000m radius if it can bank at a maximum angle
    of 40?
  • If a 300,000lb 747 is flying at 650 mph what
    angle will it have to bank at to maneuver a turn
    of 1.5 mile radius?

19
Vertical Circles
  • What forces are acting on the car? Draw a FBD...
  • What is the speed needed by a 2500kg stunt car at
    the top of a loop-the-loop of diameter 25ft in
    order to just make it through?

20
Automobile Banked Turns
  • How fast can a 1500kg car round an ice-covered
    200m radius turn if it is banked at 15 instead
    of level?

21
Banked Turns w/ friction
  • How fast can a 1500kg car round a 200m radius
    turn if it is banked at 15 and the coef. of
    friction is 0.75?

22
Satellites
  • Can you use UCM to determine the speed of a
    satellite in orbit?

23
More on Satellites
  • What limitations are put on the speed of a
    satellite in orbit for any given radius?
  • How do you change your orbital radius when in
    space?
  • Does the mass of the satellite make any
    difference?

24
Period of a Satellite
  • We can find the period of a satellite using...
  • A satellite with an orbit of exactly 24 hours is
    said to be syncronous or geosynchronous.

25
Ex Syncronous Satellites
  • Determine the altitude of a synchronous satellite
    in miles (Careful!!! The radius of the orbit
    includes the radius of the earth!)
  • Can you find its speed?

26
Life in Space
  • What are the effects of extended periods of
    weightlessness (see p. 149-150)
  • What would life on a space station be like?
  • Can gravity be simulated? How?

27
The End
Write a Comment
User Comments (0)
About PowerShow.com