Conservation of Linear Momentum

Grade 11 · Physics

Semester 1 | Period 3 | Week 15

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Subject: Physics

Semester: 1

Period: 3

Week: 15

School Name:

Teacher’s Name:

Subject: Physics

Grade Level: Grade 11

Week & Period: Week 15, Period III

Date:

Sub-topic: Conservation of Linear Momentum

 

Learning Objectives:

By the end of this lesson, learners should be able to:

  1. State the law of conservation of linear momentum.
  2. Apply the law to various collision and explosion scenarios.
  3. Solve numerical problems involving conservation of momentum.
  4. Explain practical applications of momentum conservation.

 

Previous Knowledge:

Learners understand linear momentum, impulse, and types of collisions from previous lessons.

 

Instructional Materials:

  • Dynamics carts
  • Ballistic pendulum
  • Spring-loaded launcher
  • Stopwatch
  • Meter rule
  • Graph sheets
  • Weights

 

Anticipation (Warm-Up):

Pose this scenario:
“If you fire a gun, what happens to the gun itself?”
(Demonstrates the principle of recoil as momentum conservation.)

 

Building Knowledge (Main Lesson) – 25 minutes


Experiment:

Title: Verifying Conservation of Momentum Using Dynamics Carts

Materials:

  • 2 dynamics carts
  • Smooth surface track
  • Masses
  • Spring-loaded plunger
  • Stopwatch, meter rule

Procedure:

  1. Place carts on track, one loaded with spring plunger.
  2. Measure mass and initial velocities (one is stationary).
  3. Release spring to initiate collision.
  4. Measure final velocities.
  5. Compare total momentum before and after.

Expected Result:
Total momentum before ≈ Total momentum after (within margin of error)

 

Learners’ Activities:

  • Work in pairs to simulate recoil using mass and trolleys.
  • Solve 3 numerical problems on momentum conservation.
  • Complete a momentum before/after diagram from provided data.

 

Consolidation (Review and Assessment) – 10 minutes

Oral Questions:

  • State the law of conservation of momentum.
  • In which direction does the gun move after being fired?
  • Why is it easier to move a light object quickly than a heavy one?

 

Homework / Assignment:

  • Solve: A firework of 2 kg explodes into two parts of 0.5 kg and 1.5 kg. If the smaller part moves at 12 m/s, what is the velocity of the other?
  • Research: Explain how conservation of momentum applies to rocket launch.

 

Notes – Detailed and Explained:

  • Momentum is a vector quantity; direction matters.
  • In a closed system, internal forces (like explosions or collisions) do not change total momentum.
  • Real-life applications:
    • Rocket launches: mass ejected downward gives upward motion.
    • Collisions: Car crash analysis
    • Recoil in weapons: action and reaction

 

Expanded Notes / Instructions:

  • Emphasize Newton’s 3rd Law: action and reaction pairs relate to momentum conservation.
  • Show graphical representation: momentum vs. time graphs
  • Guide through impulse-momentum connection

 

Differentiation:

  • Group learners for practicals: use real carts or simulations
  • Visual learners: Draw before-after momentum diagrams
  • High-achievers: Challenge with 2D momentum problems

 

Teacher’s Reflection:

  • Were learners able to differentiate between elastic/inelastic momentum conservation?
  • Did all learners participate in experiments?
  • Should I revisit vector addition of velocities?