Physics · Grade 11

Active learning ideas

Work Done by a Constant Force

Active learning works well for this topic because the concept of work as force times displacement can feel abstract until students physically experience the difference between effort and mechanical work. When students move, measure, and calculate their own motions, they build intuition for how force and displacement interact to transfer energy.

• Ontario Curriculum Expectations
• HS-PS3-1

• 15–40 min
• Pairs → Whole Class
• 3 activities

Activity 01

• Inquiry Circle
• 40 min · Pairs

Inquiry Circle: The Stair Climb Challenge

Students measure their mass and the vertical height of a flight of stairs. They then time themselves walking and running up the stairs. They calculate the work done against gravity and discuss why the work is the same regardless of their speed, while the 'effort' feels different.

Explain how work is a scalar quantity despite involving force and displacement vectors.

Facilitation Tip

During The Stair Climb Challenge, remind students to measure the vertical displacement rather than the total distance traveled up the stairs.

What to look for

Present students with three scenarios: 1) Pushing a box across a floor, 2) Holding a heavy box stationary, 3) A box being lifted vertically. Ask students to calculate the work done in each scenario, explaining their reasoning and identifying any forces that do zero work.

• Analyze
• Evaluate
• Create
• Self-Management
• Self-Awareness

Activity 02

• Stations Rotation
• 30 min · Small Groups

Stations Rotation: Work or No Work?

Set up stations with different scenarios: 1. Pushing a wall, 2. Carrying a heavy box across the room, 3. Lifting a weight, 4. Dropping a ball. Students must determine if 'Physics Work' is being done on the object and justify their answer using the W=Fd cosθ formula.

Analyze how the angle between force and displacement affects the amount of work done.

Facilitation Tip

In the Station Rotation, place a frictionless cart at one station so students can explore how force without displacement results in zero work.

What to look for

Pose the question: 'Imagine pushing a heavy suitcase across an airport terminal. Under what conditions would you be doing the most work, and when would you be doing no work at all?' Facilitate a class discussion focusing on the definitions of force, displacement, and the angle between them.

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

Activity 03

• Think-Pair-Share
• 15 min · Pairs

Think-Pair-Share: The Angled Pull

Students are shown a picture of someone pulling a sled at a 45-degree angle. They must explain to a partner why only a portion of their force is doing 'work' and what happens to the energy if they pull more vertically. They then share their conclusions with the class.

Construct a scenario where a large force is applied, but no work is done.

Facilitation Tip

For The Angled Pull, provide spring scales and pulleys so students can feel the difference between parallel and angled forces.

What to look for

Provide students with a diagram showing a force vector at an angle to a displacement vector. Ask them to write the formula for calculating work done in this situation and to explain in one sentence why the force component parallel to the displacement is used.

• Understand
• Apply
• Analyze
• Self-Awareness
• Relationship Skills

A few notes on teaching this unit

Teachers should emphasize the difference between biological effort and mechanical work by using real-world analogies students can relate to. Avoid starting with formal definitions; instead, let students observe work being done or not done through investigations. Research shows students grasp the concept better when they first experience the disconnect between perceived effort and actual work, then use calculations to resolve the confusion.

By the end of these activities, students should confidently define work in physics terms, explain why pushing a wall doesn't count as work, and calculate work done in various scenarios. They should also connect work to changes in kinetic energy and identify when forces do zero work.

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Watch Out for These Misconceptions

• During The Stair Climb Challenge, watch for students who think climbing stairs always involves doing work on themselves regardless of direction.

  During The Stair Climb Challenge, have students measure the vertical displacement and calculate work using the gravitational force. Ask them to explain why walking up a ramp at a low angle involves less work than climbing straight up, despite covering the same height.

• During the Station Rotation, watch for students who confuse carrying a book horizontally with doing work on the book.

  During the Station Rotation, use a force sensor to show that the vertical force holding the book up is perpendicular to the horizontal displacement. Ask students to write the work formula and identify the angle between force and displacement.

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Methods used in this brief

• Inquiry Circle
• Stations Rotation
• Think-Pair-Share