Chapter 10 Circular Motion 1 CIRCULAR MOTION Which

1. CIRCULAR MOTION • Which parts on a merry-go-round move fastest? • Which have

Types of Speed • Linear Speed = Distance/Time • Tangential Speed = Speed of

Simple & Complex Objects Motion of simple objects: Position Motion of complex objects: Position

Check Yourself A pair of wheels are connected by a chain. Which wheel has

Bicycles Notice how gears work on a modern bicycle FAST SLOW 25 -Sep-20

Circular Motion Rotational Speed: Revolutions per second Tangential Speed: Total distance per second Same

5. CENTRIPETAL FORCE • Centripetal force - center seeking force • Examples: tin can

6. CENTRIFUGAL FORCE • Centrifugal force - center fleeing force • Often confused with

7. CENTRIFUGAL FORCE IN A ROTATING REFERENCE FRAME • A frame of reference can

8. SIMULATED GRAVITY • To get a = g, the proper rotation rate and

In walking, people normally bend their knees. Why? (a) it is easier to swing

Which of the following forces is a pseudo force? (a) tension in a rope

Slides: 14

Download presentation

Chapter 10 Circular Motion

1. CIRCULAR MOTION • Which parts on a merry-go-round move fastest? • Which have greater rotational speeds? • Examples of rotational motion: Earth rotates and revolves Rotation: AKA Spin – Object moves around an internal axis. (Earth rotates around polar axis) Revolution: AKA Orbit – Object moves around an external axis. (Earth revolves around the sun)

Types of Speed • Linear Speed = Distance/Time • Tangential Speed = Speed of something moving along a circular path • Rotational Speed = Number of Rotations/Time • Note that Tangential Speed depends on the rotational speed and the distance from the axis (One complete revolution covers a distance of 2πR).

Simple & Complex Objects Motion of simple objects: Position Motion of complex objects: Position & Rotation Axis of Rotation SIMPLE 25 -Sep-20 COMPLEX Notice that the center of mass of the complex object follows the same path as the simple object

Check Yourself A pair of wheels are connected by a chain. Which wheel has higher rotational speed? By how much? 1 Faster tangential speed on rim? 25 -Sep-20 2

Bicycles Notice how gears work on a modern bicycle FAST SLOW 25 -Sep-20

Circular Motion Rotational Speed: Revolutions per second Tangential Speed: Total distance per second Same Rotational Speed Different Tangential Speeds 25 -Sep-20

5. CENTRIPETAL FORCE • Centripetal force - center seeking force • Examples: tin can and string, sling, moon and earth, car on circular path • Demo – Water in a Bucket • Demo - Loop the Loop

6. CENTRIFUGAL FORCE • Centrifugal force - center fleeing force • Often confused with centripetal • Examples: sling and bug in can • Centrifugal force is attributed to inertia. • Notice that an umbalanced force is needed to make an object travel in a circular path (centripetal)

7. CENTRIFUGAL FORCE IN A ROTATING REFERENCE FRAME • A frame of reference can influence our view of nature. • For example: we observe a centrifugal force in a rotating frame of reference, yet it is a fictitious (pseudo) force. • Centrifugal force stands alone (there is no action-reaction pair) - it is a fictitious force.

8. SIMULATED GRAVITY • To get a = g, the proper rotation rate and the proper radius must be determined. • Rotational Force = mv 2/r, so a = v 2/r = 9. 8 m/sec 2 • Gravity gradients in a rotating spacecraft • Jogging in space

Chapter 10 Review Questions

In walking, people normally bend their knees. Why? (a) it is easier to swing their legs because bending lowers the rotational inertia of their legs (b) it is easier to swing their legs because bending increases the rotational inertia of their legs

Which of the following forces is a pseudo force? (a) tension in a rope (b) force of gravity (c) centripetal (d) friction (e) centrifugal