Embedded Files
Suzanne Jensen
S ED 525Sci
3/6/12
Science Demonstration Lesson
Title: Newton’s Balloons
Principle(s) Investigated: This demonstration is based on Newton’s three Laws of Motion. The first law states that an object at rest tends to stay at rest and an object in motion tends to stay in motion, both unless the object is acted upon an outside force. The second law defines the force on an object as the amount of acceleration exerted on a mass. The third law related to this demonstration states that every action of force on an object has an equal and opposite force from the object in reaction to the force. This demonstration will show these laws with the motion of a variety of sizes of balloons (thus a variety of masses) and the resulting motion from the same forces. Students will witness the forces of the movement of air molecules in the balloon, the frictional force from the air molecules outside the balloons in front of the balloon, and the force of gravity on the movement of the balloon. The students will design ways to illustrate these forces that propel the balloon and the forces against the balloon’s movement. The students will make connections with the forces and the vector relationships then explain which balloons travel farther and what factors cause one balloon to travel farther than the others.
California Science Standards :
Motion
1. The velocity of an object is the rate of change of its position. As a basis for understanding this concept:
a. Students know position is defined in relation to some choice of a standard reference point and a set of reference directions.
b. Students know that average speed is the total distance traveled divided by the total time elapsed and that the speed of an object along the path traveled can vary.
c. Students know how to solve problems involving distance, time, and average speed.
d. Students know the velocity of an object must be described by specifying both the direction and the speed of the object.
e. Students know changes in velocity may be due to changes in speed, direction, or both.
f. Students know how to interpret graphs of position versus time and graphs of speed versus time for motion in a single direction.
Forces
2. Unbalanced forces cause changes in velocity. As a basis for understanding this concept:
a. Students know a force has both direction and magnitude.
b. Students know when an object is subject to two or more forces at once, the result is the cumulative effect of all the forces.
c. Students know when the forces on an object are balanced, the motion of the object does not change.
d. Students know how to identify separately the two or more forces that are acting on a single static object, including gravity, elastic forces due to tension or compression in matter, and friction.
e. Students know that when the forces on an object are unbalanced, the object will change its velocity (that is, it will speed up, slow down, or change direction).
f. Students know the greater the mass of an object, the more force is needed to achieve the same rate of change in motion.
g. Students know the role of gravity in forming and maintaining the shapes of planets, stars, and the solar system.
Materials:
· Balloons of various sizes and shapes, preferably the same color
· Drinking Straws, all the same size and color
· String, I used dental floss, kite string and fishing line also work
· Electrical or masking tape
· Meter stick or metric tape measure
· Stopwatch or clock, with seconds
· Dark color permanent markers
All materials can be bought in a craft store or variety store. The time piece must have a second hand or seconds timer.
Discrepant Event
Hold up one round and one oblong balloon blown up but not tied. Ask students wht they predict will happen when the two balloons are released. Compare and contrast the two resulting paths. Suggest they consider having the balloons attached to a line to direct the path of the balloon. Cound the students then compare the shape size of balloons for time and distance, velocity, of the balloons related to size and shape?
Procedure:
1. Connect a string parallel to the ground across the length of the classroom, attached at one end but temporarily attached at the other to be able to take it off to place the balloon rocket on the string for the demonstration.
2. Set out several balloons of various sizes and shapes. Having the same color will eliminate the distraction that color may have any effect on travel speed or distance. Number each balloon to later document data.
3. Blow up one balloon (blow up each balloon with the same number, say 2 or 3, puffs to attempt to give the sam evolume of air in each) and tape on a straw the length of the balloon, with the open end at the end of the straw. Do not tie the balloon tail.
4. String on the blown up balloon, draw the string taut, and attach to the wall. Hold the balloon tail until the string it tied tight.
5. Begin the seconds timer the same time the balloon is released. Stop the timer when the balloon stops moving. Measure the distance traveled.
6. Create a chart that identifies the data measured for each balloon, with a drawing or brief description of each balloon shape and size. Record the time traveled and the distance traveled along the string. Students should be able to calculate the velocity for each balloon.
7. Repeat the experiment for each balloon and record the measurements. Enter into the
8. Students should include a diagram of the demonstration.
Student prior knowledge:
1. Students have had previous lessons regarding velocity and acceleration, with investigations, real life connections, and research.
2. Students understand the amount of an object is its mass and inertia is related to the object’s mass.
3. Students worked through the conservation of momentum and the outside forces that act on an object, such as friction, gravity, and acceleration from another object.
4. Students have learned through a variety of examples and investigations the concepts of forces: balanced, unbalanced, and net.
5. Students have defined and applied Newton’s First Law of Motion, an object at rest will remain at rest, an object moving with constant velocity will continue until acted upon by an outside force.
6. Students have studied various types of forces such as friction (static, sliding, and rolling) and air resistance, and understand that this demonstration shows the effects of sliding friction.
7. Students have learned to apply Newton’s Second Law of Motion, that Force = mass X acceleration and Ft = m - m
8. Students have studied Newton’s Third Law of Motion that for every action, there is an equal but opposite reaction.
Explanation:
*I would set up the line prior to class with a very loose connection on one end that can be taken down to add the balloon/straw rocket. The materials and the observation guide should be ready prior to class, including the balloon, straws, tape, metric measure, and seconds timer.
*Students have previously studied motion, velocity, and force. This demonstration extends their understanding to encompass the concept of Newton’s third law, for every action there is an equal and opposite reaction. The balloon’s escaping air blowing out the back of the balloon is matched with the opposite motion forward of the balloon.
*Other force relationships come into play with the size and shape of the balloon including mass, air resistance, and friction. They will see the results of these influences in the differences in the times and distances traveled.
Questions & Answers:
1. Describe the balloon that traveled the farthest along the string. From the sizes and shapes of the balloons, infer what aspects of these balloon rockets made it travel the farthest.
2. Newton’s Third Law states that a force acting on an object will have an equal and opposite force reacting to that force. Relate this law to the force acting on the balloon with an illustration of the object, vectors, and general formula Newton used to compare the force, mass, and acceleration of the balloon.
3. How could the forces exerted on the balloon to make it travel along the string be used to make a vehicle move? Design and draw an object that could use these forces to travel.
Applications to Everyday Life:
1. I would provide one real application for them to build a balloon race car with recyclable materials in class. With the goal to be the fastest car in the class, they would have to apply the concepts of forces on their car in the design.
2. The aerodynamic shape of vehicles, as well as decreasing the weight and air resistance is specifically done to decrease resistance and increase fuel economy or speed.
3. A swimmer considers many factors to decrease drag and increase speed including shaving body hair, wearing skin tight swimgear, streamlined initial entry in the water, etc. for peak performance.
Photographs:
www.tartarus.org www.islandnet.com
Videos:
Instructions to Build a Balloon Car: link, http://tjebben.com/Personal%20Projects/Building%20Balloon%20Racers.PDF
Balloon Races Demonstration: link,
www.handsonlinelearning.cm/bitesmovies.htm
California Science Standards
http://www.cde.ca.gov/be/st/ss/documents/sciencestnd.pdf
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