Exploring Newton's Second Law

William Lubansky
King of Grace Elementary School
William Lubansky
King of Grace Lutheran School
Golden Valley, MN 55422
Based on an activity done by William Robertson (Stop Faking It) at science conference in 2006.
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Summary

Students will conduct an experiment that will reinforce their understanding of Newton's Second Law. Using simple objects, students will be able to control force, mass, and acceleration, and how each is related to each other.

Learning Goals

Students will conduct an experiment using the scientific process; ask a question, construct a hypothesis, test with an experiment, analyze results, and report results.
Students will be able to graph results of their experiment and compare results with other classmates. Students will demonstrate an understanding of how this experiment correlates to Newton's Second Law.

Context for Use

I've addressed standards for 4th grade because that is the grade level I use this activity. I think it could easily be expanded to challenge grades all the way up through 8th grade. I have a set of rulers, marbles, and half cups so that students can work in groups of 2 or 3. It can be done on the floor, tabletops, or desks. I would consider this a lab/inquiry lesson, and I present it over three periods of 20 minutes each. Students should already have a grasp of the three terms being used: force, mass, and acceleration.

Subject: Physics:Classical Mechanics
Resource Type: Activities:Classroom Activity:Short Activity:Demonstration
Grade Level: Intermediate (3-5), Middle (6-8)

Description and Teaching Materials

Students will set up a ramp using a rulers and books as described on the worksheet I have provided. Make sure all students are using the same books to construct their ramps. Students measure the distance the cup moves using one and two marbles dropped from the heights noted on the worksheet. After collecting the data, we create a bar graph using the data from all groups. Discussion follows focusing on how this experiment backs up Newton's Second Law. Worksheet (Acrobat (PDF) PRIVATE FILE 413kB Sep4 08)

Teaching Notes and Tips

Students need to have an understanding of the term doubling. In our experiment we have doubled the height (not necessarily the acceleration) and the mass. This experiment opens the door to an infinite amount of questions about variables. I start with three basic questions about the graph. 1. Did your distance double as you doubled the height of the marble or marbles? 2. Did the distance double when you went from one marble to two? 3. What are some variables that might have affected your results?

Assessment

During the experiment, I move about the room and make note of students' level of participation in the experiment. All students are required to hand in the worksheet with proper scientific measurements, along with a bar graph of their individual group and a copy of the classroom results.

Standards

4.I.B.1 The student will recognize when comparisons might not be fair because some conditions are not kept the same.
4.I.B.2 The student will collect, organize, analyze and present data from a controlled experiment.
4.I.B.3 The student will recognize that evidence and logic are necessary to support scientific understandings.

References and Resources