Download Circular Motion

College Physics Interactive Applets: Instructors Guide
CIRCULAR MOTION
Purpose
This applet provides visual and numerical examples of the behavior of, and relationships between, velocity, acceleration,
and force in uniform circular motion.
Using the Applet
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Note that the word TUTORIAL on the upper right is a link to online instructions for using the applet.
Configure the applet using the CONTROLS template on the right.
The vertical slider on the left side controls the angle at which you view the motion.
The Equations box just to the upper right of the animation displays equations indicating the formula, units, calculation,
and value of the acceleration and the force on the mass.
 The Graph box just to the lower right of the animation displays a graphs of the desired velocity, acceleration, and force
components as functions of time.
The Controls
 Velocity: Controls the tangential speed of the circular motion.
 Mass: Controls the mass of the ball in motion.
 Simulation Speed: This slider controls the speed of the animation as the projectile moves through the air.
 Play/Pause: Starts and stops the animation of the motion.
 Show Vectors: Displays arrows indicating the directions and magnitudes of the velocity, acceleration, and force vectors.
When VELOCITY is selected, the horizontal and vertical components are also shown.
 Graphs: Graphs the available quantities as functions of time in the Graph box left of the graphs controls.
Quick Demonstration
 After the applet loads, deselect the VELOCITY, ACCELERATION, and FORCE vectors, and the VELOCITY X,
and VELOCITY Y graphs.
 Reduce the VELOCITY of the mass to 0.5 m/s and the MASS to 1.5 kg.
 Ask the following question:
1. In what direction does the force of the mass point?
a) Always to the left.
b) Always to the right.
c) Always to upward.
d) Always to downward.
e) Always away from the center of the circular path.
f) Always toward the center of the circular path.
 Select PAUSE, and then check FORCE. Note its direction. Select PLAY to show that the force continues to point
toward the center while in motion.
 Ask the following question:
2. In what direction does the velocity of the mass point?
a) Always to the left.
b) Always to the right.
c) Always to upward.
d) Always to downward.
e) Always away from the center of the circular path.
f) Always toward the center of the circular path.
g) Always perpendicular to the force.
 Select PAUSE, and then check VELOCITY. Note its direction and the direction of its components.
 Select PLAY. Verify that the students notice and understand why the components are changing in size, while the full
vector is not.
 Note that the full velocity vector remains perpendicular to the force vector.
 Ask the following question:
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3. In what direction does the acceleration of the mass point?
a) Always away from the center of the circular path.
b) Always toward the center of the circular path.
c) Always perpendicular to the force.
d) Always in the opposite direction of the force.
 Select PAUSE, and then check ACCELERATION. Note that the red arrow is in the same direction as the force,
toward the center. Select PLAY.
 Deselect VELOCITY and ACCELERATION.
 Ask the following question:
4. What would happen to the force if I increase the velocity?
a) It will get larger.
b) It will get smaller.
c) It will not be affected.
 Click the rightmost arrow on the VELOCITY slider to gradually increase its value. Verify that the students
understand the effect it has on the force vector.
Further Study with the Textbook
 Examples 5.2 and 5.4 (page 149 and 153)
Using the default values when the applet loads, have students use some of the relationships found in these examples to
calculate the frequency, angular frequency, and period of the mass in the applet.
 Figure 10.16 (page 355)
Have students use the slider on the left to rotate to a sideways view and compare the motion as seen this way to simple
harmonic motion.
Suggested End-of-Chapter Follow-up Questions
Chapter 5: CQ-4, MCQ-2–5
Interactive Applets: CICULAR MOTION
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