Predictions Chapter 2: Magic and Motion

Chapter Challenge
In a scenario that focuses on illusions used by magicians, students are challenged to plan and present a skit or poster that explains the laws of motion in everyday life. This presentation, while entertaining and humorous, must demonstrate understanding of both the physics principles of force and motion and reflect the nature of scientific knowledge.

Chapter Summary
To develop understanding of the laws of motion and the science principles of inquiry necessary to meet this challenge, students work collaboratively on activities to learn about the affects of force on common motions. These experiences engage students in the following content identified in the National Science Education Standards.

Activity Summaries

Physics Principles

Activity One: Newton's First Law

Students are introduced to friction as a force through investigations with an air puck. After interpreting motion depicted in photographs, they read to learn more about Newton's First Law of Motion and how reducing friction affects motion.

• Newton's Laws of Motion
• Force
• Friction

Activity Two: Measuring Motion

Continuing their study of motion, students measure the time and rate at which they walk, then calculate their speed and acceleration. From this, they determine patterns for acceleration in a straight line.

• Speed
• Acceleration
• Interpreting & analyzing data

Activity Three: Forces, Acceleration, and the Missing Link

Students move large balls of different masses with a broom to discover the relationship between mass and the force needed to move a mass. This also enables them to increase their ability to differentiate between mass and weight.

• Relationships among force, mass, and acceleration

Activity Four: Changing Directions

Centripetal force is introduced when students blow on an air puck, trying to make it move in a circular fashion. The force needed to move an object in a circle is further explored by twirling objects on a string, emphasizing that the force must pull towards the center.

• Centripetal force
• Relationship among force, mass, and radii of circles
• Centripetal acceleration

Activity Five: The Traditional Cart and Book Experiment

The traditional lab experiment with a dynamics cart and book is used to explore Newton's Second Law of Motion. Students then read to connect their observations to concepts of force, mass, and acceleration.

• Newton's Second Law of Motion

Activity Six: The Modern Cart and Book Experiment

Students now use a cart and pulley connected to a computer probe to collect data on how acceleration changes when the force or mass changes. This experiment enables a quantitative understanding of Newton's Second Law of Motion.

• Force, Mass, and Weight
• Newton's Second Law of Motion

Activity Seven: Car Push

In this activity, students learn to use measures of force and acceleration to determine mass. They also learn more about the affect of friction on motion and how these concepts connect to the challenge.

• Force, Acceleration
• Friction

Activity Eight: Newton's Third Law of Motion

In an experiment with spring scales, students learn about the principle of equal and opposite forces inherent in Newton's Third Law. They then explore how this law applies to situations where the masses, and therefore the forces, appear to have large differences.

• Newton's Third Law of Motion