Chapter 5 Reading Guide

5.1 Kinematics of Uniform Circular Motion

and

5.2 Dynamics of Uniform Circular Motion

Decide if the following statements are TRUE or FALSE.

*1. One radian is a smaller angle than one degree.

*2. Centripetal acceleration is directed away from the center of the circular path of the object which is moving in circular motion.

*3. Centripetal force is directed toward the center.

4. The centrifugal force is a real force that tends to push objects away from the center when they are moving in uniform circular motion.

5. Newton’s Second Law can be applied to uniform circular motion.

Video Cinema Classics 1B Chapter 26, Chapter 24 (if time, Chapter 29)

List all of the quantities that are uniform (constant) in uniform circular motion.

What force is necessary to keep the earth moving in a circular orbit around the sun?

What questions do you have on the tetherball example on page 117?

What force does the seat of the Ferris wheel (page 119) apply to a passenger who has a mass of 80 kg and is currently at the highest point in the ride?

…currently at the bottom point of the ride? The ride is moving in a vertical circle.

5.3 A Car Rounding a Curve

Only PHY161 students will do the banked curve.

5.4 Nonuniform Circular Motion SKIP

5.5 Centrifugation

What is the goal of centrifugation?

5.6 Newton’s Law of Universal Gravitation

Decide if the following statements are TRUE or FALSE.

*1. Every mass in the universe attracts every other mass in the universe.

2. The force of gravity between two objects is proportional to the square of the distance between the two objects.

3. The mass of the earth can be determined by measuring g , G (the universal gravitational constant) and the radius of the earth.

4. The value of g is a constant everywhere in the United States.

5. The value of g for someone who is walking on Mars is less than 9.8 m/s².

6. Gravity acts without contact between the objects.

page 125 How did the astronomical knowledge of the moon’s distance from the earth and the time for 1 "revolution" of the moon around the earth help Newton develop the Law of Gravitation?

*Which is stronger, the gravitational force of the earth on the moon or the gravitational force of the sun on the moon?

How might the value of G be determined?

5.7 Gravity Near the Earth’s Surface; Geophysical Applications

g is also known as the gravitational field strength .

5.8 Satellites and "Weightlessness"

7. Satellites are always falling toward the earth as they orbit the earth.

8. Orbiting satellites have a rocket that continuously fires to prevent the satellite from crashing into the earth.

Suppose NASA wants to put a satellite into a "geosynchronous" orbit around Mars. What value should be used for the radius of the orbit? Mars mass is 6.4 x 10²³ kg. The radius of Mars is 3.32 x 10⁶ m. A "day" on Mars is approximately 24 hours 37 minutes.

5.9 Kepler’s Laws and Newton’s Synthesis Read this for concepts only.

5.10 Types of Forces in Nature Read this for concepts only.

Suppose that the Ferris Wheel ride at Adventure Land is out of control. It is rotating so fast that the passengers feel no contact force with their seats at the top of the circular motion. If the ride has a radius of 40 feet what is the speed of a person at the top of the ride? You should make a sketch of the ride with a passenger at the top of the ride. If the person weighs 150 pounds what would a bathroom scale read if the person stood on it at the bottom of the ride while the ride is in motion at this speed?

G = 6.673 x 10^-11 N m²/kg ²

Copyright© 2001 - 2006 by Greg Clements Permission is granted to reproduce this document as long as 1) this copyright notice is included, 2) no charge above photocopy costs is made, and, 3) the use is for an educational purpose. Editing of the document to suit your own class style and purposes is allowed.