John Missig

Dan Rinkoski

Topic: Newton’s Second Law of Motion

Grade: Fifth Grade

Duration: 45 minutes

Grade Level Content Expectations:

P.FM.05.34 Relate the size and change of motion to the strength of unbalanced forces and the mass of an object.

Objectives:

Students will be able to recognize the various relationships that exist between force, mass, and acceleration. For example, Students will recognize:

  • If the force exerted on an object is doubled, then the acceleration of that object is also doubled.
  • If the mass of an object is doubled, then the acceleration of that object is cut in half.
  • The greater the mass of an object, the greater the force will need to be to accelerate that object.

Engage:

Students will begin by watching a you tube video demonstrating Newton’s Second Law of Motion, F=MA. The video shows a man kicking 3 differently sized soccer balls. The man starts by kicking a regular sized soccer ball, then a slightly bigger soccer ball, and concludes by kicking a giant soccer ball. This short video will serve as a way to get students thinking about the relationships between force, mass, and acceleration. I will conduct a short class discussion following the video guiding the students to the fact that as the soccer balls got bigger, the man had to kick them harder (use more force) to cause them to move (accelerate).

Possible video questions:

What did you notice about the way each ball moved after they were kicked?

Which of the balls appeared to move the fastest? The slowest? Why do you think this is so?

Exploration:

Students will be broken up into small groups of 4 or 5 to conduct a lab that explores the relationships of force, mass, and acceleration in Netwon’s Second Law of Motion. There will be three lab stations with experiments for each group of students to conduct. Each group will spend 5 to 7 minutes at each of the stations before rotating to the next station.

Station one will deal with air resistance. Students will take two pieces of lined paper. They will crumple up one of the pieces of paper and leave the other piece as is. The students will be asked to drop each piece of paper at the same time. They will make predictions as to which piece of paper will hit the ground first, then perform the experiment and record their observations.

Station two deals with friction. Two differently sized objects (bricks, text books, wood blocks) made from the same material are place on a large table or desk. A string is tied around each of the objects and a paper clip is tied to the other end of the string. The students will take washers or small weights and hang them from the paper clips dangling off the table. The objective of this station is to get the objects to move by adding additional weight to the dangling paper clips. The students will make predictions as to which object will need more weight added to move it from its original position on the table. The students will then perform the experiment and record their observations.

Station three deals with buoyancy. At this station the students will tie a paper clip to the end of a helium filled balloon and add weight (washers) to it, and try to balance the balloon from rising to the ceiling or falling to the ground. The students will make predictions as to how much weight they think is necessary to achieve this outcome, then they will perform the experiment, and record their observations.

Explain:

After the students have conducted the experiments at each of the lab stations, I will conduct a class discussion and have each group describe what they observed. I will then show the students a power point presentation about Newton’s Second Law of Motion and explain why the students observed what they did at each of the lab stations. I will give the students a few examples of Newton’s Second Law as it applies to everyday life and explain the relationships between force, mass, and acceleration as outlined in the lesson objectives.

Elaborate:

Students will conduct another activity using a small bouncy ball and a ordinary bendy straw to further their understanding of force, mass, and acceleration. The students will blow into one end of the bendy straw while pointing it at the bouncy ball. Each group of students will have a differently sized bouncy ball. They will then draw and label a diagram of this in their science journals indicating the force applied,( breath blowing in straw) mass,( differently sized bouncy balls) and acceleration (movement of ball).

Evaluation:

There are many ways to access student understanding of these concepts. The first method for assessing understanding of content will be verified through the class discussion. I will be able to determine whether or not the students are up to speed based on their responses to the lab exploration. I will also have the students complete a small quiz on Newton’s Second Law of Motion. The quiz will include various diagrams that show force, mass, and acceleration. Questions may include;

Which object will require more force to move? Why to you think this is so?

Label the diagram. What forces are acting upon the objects? Which object has a larger mass? Which object will accelerate farther.