Physics · Grade 11

Active learning ideas

Applications of Newton's Laws (Systems)

Active learning works for applications of Newton’s Laws because students need to physically observe how forces transmit between objects and how small changes in mass or friction alter motion. When students manipulate real systems or simulations, they confront intuitive misconceptions with evidence, making abstract concepts concrete and memorable.

• Ontario Curriculum Expectations
• HS-PS2-1

• 30–50 min
• Pairs → Whole Class
• 4 activities

Activity 01

• Collaborative Problem-Solving
• 45 min · Pairs

Lab Demo: Atwood Machine Build

Provide pulleys, string, masses, and timers. Pairs assemble varying mass setups, predict acceleration using F = (m1 - m2)g / (m1 + m2), measure actual motion, and calculate percent error. Discuss why predictions match or differ in a class share-out.

Analyze how forces are transmitted between connected objects in a system.

Facilitation Tip

During the Atwood Machine Build, circulate to ensure students anchor pulleys securely and measure masses precisely to minimize measurement errors that skew results.

What to look for

Provide students with a diagram of two blocks connected by a rope on a frictionless surface. Ask them to draw the free-body diagram for each block and write the equation F=ma for each block, labeling all forces and variables.

• Apply
• Analyze
• Evaluate
• Create
• Relationship Skills
• Decision-Making
• Self-Management

Activity 02

• Stations Rotation
• 50 min · Small Groups

Stations Rotation: Multi-Body FBDs

Set up stations with scenarios: horizontal blocks with friction, inclined connected masses, vertical Atwood variants. Small groups draw FBDs on whiteboards, solve for tension and acceleration, then rotate to critique and solve next. End with gallery walk for peer feedback.

Predict the acceleration of a two-block system connected by a rope over a pulley.

Facilitation Tip

In Station Rotation: Multi-Body FBDs, assign small groups to present their free-body diagrams to the class, forcing peer scrutiny and immediate feedback.

What to look for

Present a scenario with an Atwood machine. Ask students to predict whether the heavier mass will accelerate upwards or downwards, and to write one sentence explaining their reasoning based on the net force acting on the system.

• Remember
• Understand
• Apply
• Analyze
• Self-Management
• Relationship Skills

Activity 03

• Collaborative Problem-Solving
• 30 min · Individual

PhET Simulation: Force Challenges

Use online pulley sim. Individuals adjust masses, friction, predict outcomes, run trials, and graph acceleration vs. mass ratio. Pairs then compete to match real data from class lab.

Construct free-body diagrams for each object in a multi-body system.

Facilitation Tip

With PhET Simulation: Force Challenges, pause the simulation mid-activity to ask students to predict changes before altering variables, reinforcing cause-and-effect reasoning.

What to look for

Pose the question: 'In a system of two blocks connected by a rope, is the tension force an internal or external force? Explain how your answer affects the calculation of the system's acceleration.' Facilitate a class discussion on the role of internal forces.

• Apply
• Analyze
• Evaluate
• Create
• Relationship Skills
• Decision-Making
• Self-Management

Activity 04

• Collaborative Problem-Solving
• 35 min · Whole Class

Whole Class Prediction Relay

Project escalating system problems. Students vote predictions via hand signals, test with demo equipment, explain results. Relay builds to full class derivation of system equations.

Analyze how forces are transmitted between connected objects in a system.

Facilitation Tip

For the Whole Class Prediction Relay, have students physically stand up when they agree with a prediction and sit down when they disagree, creating visible engagement and quick consensus checks.

What to look for

Provide students with a diagram of two blocks connected by a rope on a frictionless surface. Ask them to draw the free-body diagram for each block and write the equation F=ma for each block, labeling all forces and variables.

• Apply
• Analyze
• Evaluate
• Create
• Relationship Skills
• Decision-Making
• Self-Management

A few notes on teaching this unit

Teachers should start with simple systems and gradually increase complexity, ensuring students master free-body diagrams before combining multiple objects. Avoid rushing to equations until students can explain why forces act where they do. Research suggests students learn best when they first predict outcomes, then test them, then reconcile any mismatches through discussion. Emphasize the role of internal forces early, as these often confuse students more than external forces.

Successful learning looks like students accurately drawing free-body diagrams for each object in a system, correctly identifying tension, friction, and external forces, and solving for accelerations using F = ma at both the individual and system levels. Students should articulate how internal forces affect the system differently than external forces and justify predictions with calculations.

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Watch Out for These Misconceptions

• During Station Rotation: Multi-Body FBDs, watch for students assuming tension is equal throughout a rope even when friction or mass is present.

  Provide force sensors at different points along the rope in the station. Ask students to record tension values at each segment and compare them, prompting revisions to their free-body diagrams based on collected data.

• During Lab Demo: Atwood Machine Build, watch for students believing the heavier mass accelerates at the same rate as if it were alone.

  Have students calculate the expected acceleration assuming the heavier mass acts alone, then compare it to the observed acceleration. Guide them to recognize that the system’s total mass must include both objects in the equation.

• During Station Rotation: Multi-Body FBDs, watch for students including direct contact forces between connected objects in their free-body diagrams.

  Provide whiteboards and markers at each station. Ask groups to defend their diagrams to peers, focusing on how forces are transmitted via tension or normal forces rather than direct pushes.

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Methods used in this brief

• Collaborative Problem-Solving
• Stations Rotation