# Newton's 3rd Law: Skateboard Activity - Newton's Laws Expo (8 of 9)

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## Objective

Students will be able to use a skateboard and a large mass to experiment with Newton's 3rd Law.

#### Big Idea

When you toss a medicine ball it causes an equal and opposite force that is normally never observed. However, do it while on a skateboard and Newton's 3rd Law can be seen.

## NGSS Background

This lesson is based on California's Middle School Integrated Model of NGSS.

MS-PS2 Motion and Stability: Forces and Interactions

PE: MS-PS2-1 - Apply Newton's Third Law to design a solution to a problem involving the motion of two colliding objects.

DCI: PS2.A - For any pair of interacting objects, the force exerted by the first object on the second object is equal in strength to the force that the second object exerts on the first, but in opposite directions (Newton's 2nd Law).

Science and Engineering Practices7: Engaging in Arguments from Evidence

Crosscutting Concept: Cause and Effect

This activity can be used as a stand alone lesson or can be placed with eight other lessons, designed as an exposition to be experienced over three days.

Newton's Laws Expo contains:

I have also developed three demonstrations of Newton's Laws

Demonstrations

In this lesson, students engage in a short (eight minute) activity designed to demonstrate one of Newton's Laws. A student on a skateboard throws a medicine ball, causing the skateboard and the student to move backwards in the opposite direction (MS-PS2-1). The harder the student is able to throw the medicine ball, the farther and faster the skateboard and the student will travel in the opposite direction (PS2.A). It is the student's responsibility to use evidence recorded during the activity to determine that Newton's 3rd Law is being expressed, showing the equal and opposite relationship between action and reaction forces (SP7). Each activity has been carefully chosen to replicate a specific effect (CCC).

## Set-up

45 minutes

Needed Material

1. Skateboard
2. Helmet
5. Medicine Ball or old soccer ball filled with sand and duct taped together

TIP: Thrift stores are good resources for old skating equipment.

Print out a copy of Station Markers. Tape 'Station 8' marker card down to the desk where you intend students will conduct this activity. Each station marker identifies where the activity will take place and provides directions for completing the activity.

Print out a copy of Newton's Laws Exposition packet for each student. The packet includes directions and questions to answer. If you are performing this lesson as a single activity you will only need to print out Activity 8.

This activity is designed to accompany other Newton's Laws Activities. I run this unit as a three day exposition. Day 1 is reserved for showing the students all of the nine activities. Days 2 and 3 allow for an eight minute rotation. I typically have my students experience five activities (40 minutes) on Day 2 and four activities (32 minutes) on Day 3 followed by a recap of the events.

## Student Activity

8 minutes

Newton's Third law will be in effect for this lesson. Newton's Third Law states that for every action there is an equal and opposite reaction.

Students will not know what specific law of motion they will be experimenting with. They have to record what they see, gather evidence, and argue about what law is being manipulated.

Directions

1. Choose one person with skateboard experience.
2. Put on the helmet, knee pads, elbow pads, and wrist guards.
3. Sit on the skateboard holding the medicine ball.
4. All members stand around to catch any falls.
5. Throw the medicine ball forward.

Student Work Sample

## Extensions

45 minutes

Newton's Law are expressed in a multitude of ways in the English language because Newton's original text ' Philosophiæ Naturalis Principia Mathematica', often referred to as the 'Principia', was written in Latin (as were all scientific articles in that time) and translated into English. As such, there are many different translations, causing confusion with students.

I teach Newton's Three Laws using this translation:

1. An object in motion will reamin in motion and an object at rest will remain at rest - unless acted upon by another force.
2. Acceleration is based on force and mass (F=ma).
3. For every action there is an equal and opposite reaction.

To assist in teaching Newton's Law before this lesson is taught, I have included three Powerpoint lessons: