Lesson Plan
The Great Tug-of-War Lesson Plan
Students will be able to use a model to illustrate that balanced forces acting on an object result in no change in its motion (the object remains at rest or moves at a constant speed).
Understanding balanced forces is fundamental to grasping Newton's First Law of Motion and predicting how objects will behave in various situations.
Audience
7th Grade Students
Time
45 minutes
Approach
Through interactive simulation and diagramming
Materials
The Balancing Act Slide Deck, Virtual Tug-of-War Game, and Balanced Forces Diagramming Worksheet
Prep
Teacher Preparation
15 minutes
- Review the The Great Tug-of-War Lesson Plan and all linked materials.
- Ensure access to computers/tablets for the Virtual Tug-of-War Game.
- Print copies of the Balanced Forces Diagramming Worksheet for each student.
- Prepare to project the The Balancing Act Slide Deck.
Step 1
Warm-Up: Revisiting Net Force (5 minutes)
5 minutes
- Begin with a quick review of net force, asking students to recall its definition and how it's calculated.
- Use Slide 2 of the The Balancing Act Slide Deck to prompt discussion.
- Ask: "What happens when forces are unequal?"
Step 2
Introduction to Balanced Forces (10 minutes)
10 minutes
- Introduce the concept of balanced forces using a real-world example, like a book resting on a table.
- Explain that balanced forces result in zero net force and no change in an object's motion (either staying still or moving at a constant speed).
- Utilize Slides 3-5 of the The Balancing Act Slide Deck to illustrate these concepts.
- Facilitate a brief discussion on initial student understanding.
Step 3
Virtual Tug-of-War Simulation (15 minutes)
15 minutes
- Distribute devices or direct students to access the Virtual Tug-of-War Game.
- Guide students through the simulation, encouraging them to experiment with different force combinations to achieve balanced forces.
- Have students record their observations regarding object motion when forces are balanced.
- Prompt students to share their findings and discuss how the simulation demonstrates balanced forces.
Step 4
Diagramming Balanced Forces (10 minutes)
10 minutes
- Distribute the Balanced Forces Diagramming Worksheet.
- Instruct students to complete the worksheet, drawing force diagrams for various scenarios involving balanced forces.
- Circulate and provide support, ensuring students correctly represent forces and understand the concept of equilibrium.
- Review selected diagrams as a class, discussing common misconceptions and reinforcing correct understanding.
Step 5
Real-World Connections & Wrap-Up (5 minutes)
5 minutes
- Revisit the discussion on real-world examples of balanced forces. Use Slide 6 of the The Balancing Act Slide Deck.
- Ask students to identify instances of balanced forces in their daily lives.
- Conclude by summarizing the key takeaway: balanced forces lead to no change in motion.
- Distribute an exit ticket or conduct a quick poll to gauge student comprehension.
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Slide Deck
Forces in Action: A Quick Review!
What is a force?
What is net force?
What happens when forces are unequal?
Welcome students and introduce the day's topic. Briefly review the concept of force and net force from previous lessons. Ask students to share their understanding of what happens when forces are unequal. This sets the stage for introducing balanced forces.
What are Balanced Forces?
Imagine a book sitting still on a table. Why isn't it moving?
Balanced forces occur when multiple forces acting on an object cancel each other out.
This results in a net force of zero!
Introduce the concept of balanced forces with a simple, relatable example. Acknowledge prior knowledge and build upon it.
No Change in Motion!
When forces are balanced, an object will:
- Stay at rest (if it was already still)
- Continue moving at a constant speed in the same direction (if it was already in motion)
Think about it: If you push on a wall, does the wall move? No, because the wall pushes back with an equal and opposite force!
Explain the key outcome of balanced forces: no change in motion. Emphasize that 'no change in motion' includes objects remaining at rest AND objects moving at a constant speed.
Tug-of-War: Balanced or Unbalanced?
In a tug-of-war, what happens if both teams pull with the exact same strength in opposite directions?
Discussion: How does this relate to balanced forces?
Use a visual example of a tug-of-war to help students visualize balanced forces. Ask them to predict what happens if both teams pull with the same strength.
Time for the Virtual Tug-of-War!
Get ready to explore balanced forces in action!
We'll be using the Virtual Tug-of-War Game to experiment with different forces and see their effects on motion.
Introduce the virtual tug-of-war game as the next activity. Explain that they will be able to apply what they've learned about balanced forces.
Balanced Forces: Everywhere You Look!
Can you think of other real-world examples where balanced forces are at play?
- A car parked on a flat road
- A bird gliding at a constant altitude
- You sitting in your chair right now!
Remember: Balanced forces mean no change in motion!
Review the concept and ask students to think of real-world applications. This helps solidify their understanding and connect it to their own experiences.
Game
Virtual Tug-of-War Game: Explore Balanced Forces
Objective: To visually demonstrate how balanced forces result in no change in an object's motion.
Instructions:
- Access the Simulation: Imagine you are using an online simulation (e.g., a PhET simulation or similar physics interactive) that allows you to apply forces to an object, like in a tug-of-war.
- Choose Your Players/Forces: Select different forces (represented by players or arrows) to apply to an object in opposing directions.
- Observe Motion: Pay close attention to the object's movement (or lack thereof) as you apply and adjust the forces.
- Experiment with Balanced Forces:
- Try to make the forces on both sides equal. What happens to the object?
- Can you get the object to stay perfectly still?
- Can you get the object to move at a constant speed across the screen?
- Record Observations: Note down the force values you used and the resulting motion of the object. What patterns do you notice?
- Discuss: Be prepared to discuss your findings with the class. How does this simulation help you understand balanced forces?
Worksheet
Balanced Forces Diagramming Worksheet
Name: _____________________________
Instructions: For each scenario below, draw a force diagram (also known as a free-body diagram) showing all the forces acting on the object. Make sure the arrows represent the direction and relative magnitude of the forces. If the forces are balanced, the object should be at rest or moving at a constant velocity.
Scenario 1: Book on a Table
A book is resting on a flat table.
- Draw the forces:
- Are the forces balanced? __________________
- What is the net force? __________________
- What is the book's motion? __________________
Scenario 2: Two People Pushing a Box
Two people push on a large box from opposite sides. Person A pushes with 100 N of force to the right, and Person B pushes with 100 N of force to the left. The box does not move.
- Draw the forces:
- Are the forces balanced? __________________
- What is the net force? __________________
- What is the box's motion? __________________
Scenario 3: Tug-of-War Tie
In a game of tug-of-war, Team Red pulls with 500 N of force to the left, and Team Blue pulls with 500 N of force to the right. The rope remains perfectly still.
- Draw the forces:
- Are the forces balanced? __________________
- What is the net force? __________________
- What is the rope's motion? __________________
Scenario 4: Satellite in Orbit
A satellite is orbiting Earth at a constant speed and altitude. (Assume air resistance is negligible.)
- Draw the forces:
- Are the forces balanced? __________________
- What is the net force? __________________
- What is the satellite's motion? __________________
Challenge Scenario: Elevator at Constant Speed
An elevator is moving upwards at a constant speed.
- Draw the forces:
- Are the forces balanced? __________________
- What is the net force? __________________
- What is the elevator's motion? __________________