Materials Included In Kit

Additional Materials Required

Safety Precautions

The materials in this kit are considered nonhazardous. Please follow all normal laboratory safety guidelines.

Disposal

Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. Balloons may be disposed of in the trash. The air pucks are reusable and should be stored for future use.

Lab Hints

• Enough materials are provided in this kit for 30 students working in pairs or for 15 groups of students. This laboratory activity can reasonably be completed in one 50-minute class period or extended at the discretion of the teacher.
• The best results are obtained when using a smooth, level surface such as a tabletop or the floor.
• To reduce drag, distribute any added mass evenly over the surface of the air puck. Washers with a ½" diameter may fit over the stem of the air puck.
• Remind students to complete the Setup before each experiment. The pucks must levitate to provide near frictionless conditions.
• Be creative—allow students the opportunity to experiment with other collision scenarios (i.e., using multiple pucks). What other ways can Newton’s laws of motion be applied to the puck system?
• Remind students that horseplay is not allowed. Creativity and curiosity are encouraged but, seeing how hard pucks can collide is not the point of this lesson.
• Replace the balloons if they become too stretched out or if they tear. Flinn Scientific sells replacement balloons (Catalog No. AP6420).

Sample Data

Answers to Questions

1. What type of collision occurs with air pucks? What evidence leads you to this conclusion?
   Elastic. The total kinetic energy did not change as a result of the collisions.
2. Suggest other experimental setups to model Newton’s Laws of Motion.
   Students answers will vary; accept (and perform, if time allows) all reasonable experimental suggestions.

Introduction

Investigate two-dimensional collisions and Newton’s laws of motion using air pucks powered by balloons. Illustrate inertia, velocity and acceleration of the air pucks as they glide across a smooth surface riding on a cushion of air.

Concepts

• Collisions
• Velocity
• Newton’s laws of motion
• Acceleration

Background

Collisions only occur in systems containing more than one object. When objects that are made of hard materials (e.g., steel, glass, hard plastic) collide, elastic collisions occur resulting in objects bounding off of one another. When soft or sticky objects collide, the type of collision that results is referred to as inelastic. The difference between an elastic and inelastic collision depends on the kinetic energy of the objects before and after colliding. After two objects collide during an inelastic collision, the two objects stick together and move as one object. Kinetic energy does not change as a result of an elastic collision and decreases as a result of an inelastic collision.

Newton’s First Law of Motion is called the law of inertia. If an object is in motion with a constant velocity, the object tends to stay in motion maintaining that velocity unless acted upon by an external force. If an object is at rest, the object tends to stay at rest unless acted upon by an external force. Inertia may be defined as the tendency of an object to resist change in motion.

Newton’s Second Law of Motion states that force applied by an object is equal to the mass of the object multiplied by the object’s acceleration (Equation 1). In relation to acceleration, the mass of an object is inversely proportional and the force needed to accelerate the object is directly proportional. In other words, if the same force were applied to two objects of different masses, the object with less mass would experience a greater acceleration than the more massive object.

Experiment Overview

The purpose of this experiment is to investigate Newton’s laws of motion. A device called an air puck will be set in motion on a smooth surface by a gentle push from the investigator. The motion of the pucks in given situations will be observed and explained in terms of Newton’s laws of motion.

Materials

Safety Precautions

The materials in this kit are considered nonhazardous. Please follow all normal laboratory safety guidelines. Horseplay or aggressive pushing of the pucks is not permitted.

Procedure

Setup

1. Inflate one balloon and twist (but do not tie) the neck shut to prevent air from escaping.
2. Without allowing the neck to untwist, carefully stretch the mouth of the balloon over the stem of the air puck assembly. Note: The balloon will tear if overstretched.
3. To levitate the puck, untwist the neck of the balloon.
4. Gently push the puck to accelerate it over any smooth surface.
5. Repeat steps 1–4, as often as necessary.
6. To change the mass of the puck, add washers or pennies to the puck surface, and then repeat steps 1–4.

Collisions

7. Gently push two pucks without added weights toward each other.
8. Record observations of the collision on the worksheet in terms of the type of collision and any acceleration that occurred.

Newton’s First Law of Motion

9. Gently push a puck and notice if the direction and speed (velocity) appears to remain constant or changes before the balloon fully deflates.
10. Record observations on the worksheet stated in terms of Newton’s First Law of Motion.
11. Gently push one puck toward a levitating stationary puck.
12. Record observations of the collision on the worksheet. Describe the observations in terms of Newton’s First Law of Motion.

Newton’s Second Law of Motion

13. Gently push one puck toward a levitating stationary puck.
14. Record observations of the collision on the worksheet. Describe the observations in terms of Newton’s Second Law of Motion.
15. Add mass to a levitating stationary puck and gently push another puck toward the more massive puck. Note: Repeat with three different amounts of mass.
16. Record observations of the collision on the worksheet. Describe the observations in terms of Newton’s Second Law of Motion.

Newton’s Third Law of Motion

17. Repeat step 7. Try to push both pucks with the same amount of force.
18. Record observations of the collision on the worksheet. Describe the observations in terms of Newton’s Third Law of Motion.
19. Consult your instructor for appropriate disposal procedures.

Student Worksheet PDF

13243_Student1.pdf