The Arizona STEM Acceleration Project

Newton’s 2nd law - More force = More acceleration

Newton’s 2nd law - More force = more acceleration

A 7/8 grade STEM lesson

Mayra Ramos

4/15/2023

Notes for teachers

Make sure you have ample space for students to demonstrate the 2nd law of motion and give them cleaning supplies, paper towels will suffice.

The objects used do not have to be the ones in this lesson, they can be various objects with varying masses.

List of Materials

• Video of asteroids hitting the moon or earth/ videos of divers displacing water upon their descent into the water.
• Pictures of other things making craters or dents into another object.
• Markers, pencils, or color pencils
• Objects with different masses - eggs (if available)
• Sandwich bags
• Rubber bands
• Chart paper per group
• Recording Device for student groups
• Weighing scale, Rulers
• To share videos create a shared drive for students to upload videos
• *If students have limited access to technology have them create posters instead of videos

Standards (IB Standards)

Mathematics:

Year 3 Objectives:

Objective D: Applying mathematics in real-life contexts

• i. Identify relevant elements of authentic real-life situations

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Science:

Year 3 Objectives:

Objective A: Knowing and understanding

• ii. applying scientific knowledge and understanding to solve problems set in familiar and unfamiliar situations

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Standards (Arizona)

Sci - 7.P2U1.2 - Develop and use a model to predict how forces act on objects at a distance.

Sci - 7.P3U1.3 - Plan and carry out an investigation that can support an evidence-based explanation of how objects on Earth are affected by gravitational force.

Sci - 7.P3U1.4 - Use non-algebraic mathematics and computational thinking to explain Newton's laws of motion.

Math - 7.EE.B - Solve Mathematical problems and problems in real-world context using numerical and algebraic expressions and equations.

Objective(s):

Today I will be able to demonstrate and explain how Newton’s second law of motion works and affects our daily lives.

Today I will be able to give my own examples of Newton’s 2nd law and explain what is meant by: how more force = more acceleration

Today I will be able to calculate force, mass and acceleration using the formulas for Newton’s 2nd law.

Agenda (~60 mins)

Learning progression:

Intro: (5 mins)

Group discussion (2 mins)

Intro of law (5-10 mins)

Class Example (5 mins)

Group work (5-7 mins)

Review (3 mins)

Group work videos(15 mins)

Presentations (15 mins)

Teacher Slide

Agenda (~60 mins)

1. Investigating the 2nd law of Newton through pictures and videos.
2. Group discussion
3. How is the law represented in what we see?
4. Class examples
5. Group examples and calculations
6. Video/poster
7. Share and present

Learning Progression

1. T will show video and picture examples of the second law of motion with no context. Students think what is happening in each example
2. T - (place the pictures in the middle of a chart paper on each table)
3. Without speaking, students will get up and write what they think each of the pictures have in common, quickly display these for the class to see.
4. S will discuss and come up with what they think is happening and make edits and additions to their posters
5. As a class combine all their thoughts to come up with what is happening
6. Introduce the second law of motion with the formula f=ma also show what the formula looks like when calculating for mass and acceleration.
7. Introduce or review vocabulary. explain how the greater the mass or acceleration the greater the force.
8. Class Example: what is the force needed to accelerate a 30kg shipping cart 3m/s?
9. Using one of the objects, show the class how dropping an object (preferably round objects with similar sizes but not masses) onto sand will create a crater, change the mass, change the force and change the acceleration (one at a time) to show students how these affect and are part of the 2nd law of motion. Calculate.

Next slide…

Learning Progression cont..

10. Group examples: Have the kids experiment and discuss how the different objects affect the sand. The students will weigh all the objects to find the mass. Students are looking for the force the objects are making (mass x acceleration) for this experiment acceleration will = gravity (9.8m/s/s).

11. Once students are comfortable with the experiment and calculations, have them record in slow motion one of the experiments and explain them using the calculations and verbal descriptions.

12. Give feedback and present

Intro/Driving Question/Opening

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How does mass affect acceleration and force?

The mathematical representation of the consequences of nature's laws can be explored through scientific and technical innovation.

Factual: What are Newton's three laws and their mathematical equations?

Conceptual: How are the three laws interconnected?

Debatable: Does every action have an equal opposite reaction?

What do we notice in these pictures?

Video Example

https://youtu.be/x23PBJd3iKw

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Directions

• On your tables, there is a chart paper with the same pictures as the screen.
• Think (in your mind) about what is happening in the pictures and what you saw in the video
• Using the markers provided, write down (around the pictures) what you think is happening. Think Newton’s laws.
• How are they related?

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• Next discuss with your team the information you put down on the paper.
• What are we observing in the video and pictures?

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Newton’s Second Law of Motion

Force = Mass x Acceleration

The magnitude of force is equal to mass multiplied by acceleration.

Vocabulary

Force: The net force acting on the object measured in Newton’s (n)

Mass: The mass of the object, measured in kilograms (kg)

Acceleration: The acceleration of the object, measured in meters per second squared (m/s/s)

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Let’s Practice (Class)

What is the force needed to accelerate a 30kg shipping cart 3m/s?

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*Egg = .06kg

*plastic egg = .03kg

*Gravity = 9.8 m/s/s

Let’s Practice (Groups)

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In your groups,

1. Weigh each object provided to find the mass
2. We will use gravity as the acceleration pull = 9.8m/s/s
3. You will conduct similar experiments as our egg experiment with different objects and calculate the force.
4. Record the dept of the crater made so you can discuss with the class how force effects the impact made.

Video!

• In groups of 3-4, you will record one of your experiments in slow motion and explain in mathematical calculations and in words how mass affects force and acceleration.

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Assessment

Explain why this is right or wrong

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1. 2.

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Both are traveling at 10m/s/s. The bike has more force.

Differentiation

Display the definitions for these students on the board. Also, have step by step directions on how to mathematically calculate the 2nd law of motion for students who struggle with the math portion of the law.

Remediation

Extension/Enrichment

For students who are ready to calculate the different variations of the 2nd law of motion, allow them to continue working on finding mass and acceleration.

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Have these students experiment with other objects that are affected by their shapes and have them discover why these objects fall differently.