A Lesson Plan on the Second Law of Motion

By Kathy Foust

Use this lesson plan and science activity to develop students' knowledge of Newton's Second Law of Motion. This motion lesson plan provides hands on activity as well as explanations and study guides.

Helping Students Understand Mass in Motion

Before beginning the activity below, be sure that students understand the concept of motion and all its terms along with Newton's First Law of Motion. These concepts will be applied in this science activity.

Discuss how external unbalanced forces are required to produce a change in velocity. This change in velocity results in a change in acceleration. The mass of an object also has an impact on acceleration. The larger the mass, the lower the acceleration; unless, the change in velocity is increased with the increase in mass. Use this information to help students complete the activity below.

An Activity to Drive Home the Teaching

Explain to students that Newtons Second Law of Motion states that force is equal to mass times acceleration where force and acceleration are directly proportionate to each other. This direct proportion can also cause an inverse proportion if the amount of the mass or acceleration changes and the force does not. Use the activity below to demonstrate this law. You will need 2 one gallon jugs of water, a rope and a pulley.

1. Hang the rope from the pulley with equal lengths on either side.
2. Fill one gallon of water halfway and fill the other gallon of water all the way.
3. Tie each gallon to opposite ends of the rope, holding each gallon at an equal distance from the floor.
4. Let go of the gallons.
5. Discuss the fact that the fuller gallon used force to pull the half-gallon further from the floor. It was able to do this because the force of gravity was applied to the full gallon.
6. Empty the half-gallon.
7. Perform the same experiment again. This time the empty gallon goes up even faster than the first time and the full gallon comes down quicker. Discuss how the changes in mass effected the acceleration as well as the force in this experiment.
8. Repeat the experiment using various levels of water each time.

Discuss the implications of this law with students. How can this have an impact on nature? For instance, use Newton's Second Law of Motion to discuss the following questions.

• Think of a tree broken in half by a wind storm. What changes were applied to cause enough force to break the tree?
• Think of playing on a teeter totter as a child. How did mass impact force in this situation? How did acceleration have an impact on force?

Continue to discuss various scenarios with your students until you are sure they understand Newton's Second Law of Motion. To create further understanding of Newton's Second Law of Motion, refer students to the study guide on Newton's Second Law of Motion.