Circular motion
Download
1 / 17

Circular Motion - PowerPoint PPT Presentation


  • 72 Views
  • Uploaded on

Circular Motion. Uniform Circular Motion. Speed is constant, VELOCITY is NOT. Direction of the velocity is ALWAYS changing. Period (T) = time to travel around circular path once. (C = 2 π r). We call this velocity, TANGENTIAL velocity as its direction is TANGENT to the circle.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Circular Motion' - sugar


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.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Uniform circular motion
Uniform Circular Motion

Speed is constant, VELOCITY is NOT.

Direction of the velocity is

ALWAYS changing.

Period (T) = time to travel around circular path once. (C = 2πr).

We call this velocity, TANGENTIAL velocity as its direction is TANGENT to the circle.


Centripetal acceleration
Centripetal Acceleration

θ

Dv

v

v

Centripetal means “center seeking” so that means that the acceleration points towards the CENTER of the circle.

v

v

q


Drawing the directions correctly
Drawing the Directions correctly

So for an object traveling in a counter-clockwise path. The velocity would be drawn TANGENT to the circle and the acceleration would be drawn TOWARDS the CENTER.

To find the MAGNITUDES of each we have:


Circular motion and n s l
Circular Motion and N.S.L

Recall that according to Newton’s Second Law, the acceleration is directly proportional to the Force. If this is true:

NOTE: The centripetal force is a NET FORCE. It could be represented by one or more forces. So NEVER draw it in an FBD.


Examples
Examples

The blade of a windshield wiper moves through an angle of 90 degrees in 0.28

seconds. The tip of the blade moves on the arc of a circle that has a radius of 0.76m. What is the magnitude of the centripetal acceleration of the tip of the blade?


Examples1
Examples

What is the minimum coefficient of static friction necessary to allow a penny to rotate along a 33 1/3 rpm record (diameter= 0.300 m), when

the penny is placed at the outer edge of the record?

Top view

FN

Ff

mg

Side view


Satellites in circular orbits
Satellites in Circular Orbits

Consider a satellite travelling in a circular orbit around Earth. There is only one force acting on the satellite: gravity. Hence,

Fg

There is only one speed a satellite may have

if the satellite is to remain in an orbit

with a fixed radius.


Examples2
Examples

Fg

Venus rotates slowly about its axis, the period being 243 days. The mass of Venus is 4.87 x 1024 kg. Determine the radius for a synchronous satellite in orbit around Venus. (assume circular orbit)

1.54x109 m


Welcome
Welcome

Today, Mr. Souza will give some notes about banked curves and vertical circular motion.

You may

  • Sit in the first several rows in order to join the discussion about the above two topics

    OR

  • Sit towards the back part of the room and begin work on tonight’s homework:

    • C&J p.150 # 21, 24, 26, 35, 36, 37, 40, 42


Banked curves
Banked Curves

FN

FN cos(θ)

θ

A car of mass, m, travels around a banked curve of radius r.

FN sin(θ)

θ

W=mg


Banked curves example
Banked Curves Example

FN

FN cos(θ)

θ

Design an exit ramp so that cars travelling at 13.4 ms-1 (30.0 mph) will not have to rely on friction to round the curve (r = 50.0 m) without skidding.

FN sin(θ)

W=mg

θ


Vertical circular motion
Vertical Circular Motion

Gratuitous Hart Attack

NT

mg

mg

mg

NL

NR

NB

What minimum speed must she have to not fall off at the top?

mg


Vertical circular motion1
Vertical Circular Motion

What minimum speed must she have to not fall off at the top?

NT

mg


Examples3
Examples

mg

T

The maximum tension that a 0.50 m string can tolerate is 14 N.

A 0.25-kg ball attached to this string is being whirled in a vertical circle.

What is the maximum speed the ball can have

(a) at the top of the circle, and

(b)at the bottom of the circle?

(a)


Examples4
Examples

(b) At the bottom?

T

mg


Homework
Homework

  • C&J p.150 # 21, 24, 26, 35, 36, 37, 40, 42

  • Please watch these two video clips (they relate to problem #37).

    • http://www.youtube.com/watch?v=v1VrkWb0l2M

    • http://www.youtube.com/watch?v=2V9h42yspbo

      Homework problems and links to video clips will be posted on Mr. Souza’s ASD site.


ad