# Newton's 2nd Law: Ping Pong Ball Activity - Newton's Laws Expo (5 of 9)

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## Objective

Students will be able to test Newton's 2nd Law of motion using ping pong balls and golf balls.

#### Big Idea

Striking a ping pong ball and a golf ball with a ruler creates differing amounts of acceleration.

## 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-PS2-2 - Plan an investigation to provide evidence that the change in an object's motion depends on the sum of the forces on the object and the mass of the object.

DCI: PS2.A - The motion of an object is determined by the sum of the forces acting on it; If the total force the object is not zero, its motion will change (Newton's 1st Law). The greater the mass of the object the greater the force needed to achieve that same change in motion. For any given object, a larger force causes a larger change in motion (Newton's 2nd Law).

Science and Engineering Practices (7) Engaging in Arguments from Evidence

Crosscutting Concept (2) 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

With this lesson, students engage in a short (eight minute) activity designed to demonstrate one of Newton's Laws. The acceleration of a ping pong ball will be compared to the acceleration of a golf ball when a constant force is applied (MS-PS2-2). The large mass (golf ball) should show a lower acceleration then the small mass (ping pong ball) (PS2.A). It will be the student's responsibility to use evidence recorded during the activity to determine that Newton's 2nd Law is being expressed, show the connection between force (F), mass (m), and acceleration (a) (SP7). Each activity has been carefully chosen to replicate a specific effect (CCC).

## Set-up

5 minutes

Needed Material

1. Wooden rulers
2. Ping Pong balls
3. Golf balls

Print out a copy of Station Markers. Tape 'Station 5' 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 5.

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 all the students 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 Second Law will be in effect for this lesson. Newton's Second Law states that acceleration (a) is based upon force (F) applied to the object and the mass (m) of the object. A change in force or mass will change the object's acceleration. This law can be summed by the formula F=ma (Force = mass X acceleration).

Students will not know what specific law of motion they will be experimenting with. They will have to record what they see, gather evidence and use this to make an informed decision as to which law this activity address. Then they use argumentation, based upon their evidence, to discuss what law is being manipulated.

Directions

There are two sets of directions to experience Newton's 2nd Law: 1) Constant Force, and 2) Constant Acceleration.

 Constant Force 1) Place a ping-pong ball in front of the wooden ruler. 2) Carefully bend the ruler back and release it. 3) Record your observations 4) Place a golf ball in front of the wooden ruler. 5) Carefully bend the ruler back and release it. Be sure to bend the ruler back to the same spot (force needs to be constant). 6) Record your observations. Constant Acceleration 1) Place a ping-pong ball in front of the wooden ruler. 2) Carefully bend the ruler back and release it. 3) Record your observations 4) Place a golf ball in front of the wooden ruler. 5) Carefully bend the ruler back and release it. Be sure to bend the ruler back to achieve the same acceleration as the ping-pong ball (acceleration needs to be constant). 6) Record your observations.

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 with this translations.

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