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Subject: Physics
Semester: 2
Period: 6
Week: 34
School Name:
Teacher’s Name:
Subject: Physics
Grade Level: Grade 10
Week & Period: Week 34, Period VI
Date:
Sub-topic: Elasticity and Hooke’s Law (Young’s Modulus)
Learning Objectives: By the end of the lesson, learners should be able to:
- Define elasticity and Hooke’s Law.
- Explain elastic limit, limit of proportionality, and plastic deformation.
- Interpret stress, strain, and Young’s modulus.
- Solve numerical problems involving Hooke’s Law.
- Represent elasticity graphically.
Instructional Materials:
- Springs of varying stiffness
- Slotted weights
- Metre rule
- Retort stand and clamp
- Graph paper
- Wire (e.g., copper or nichrome)
Anticipation (Warm-Up): Pose this challenge: “What happens if you keep pulling a spring longer and longer?” Allow students to test this with real springs and observe behavior.
Building Knowledge (Main Lesson):
- Elasticity: The ability of a material to return to its original shape after being stretched or compressed
- Hooke’s Law: F = kx, where F is force, k is spring constant, x is extension
- Stress = Force / Area, Strain = Extension / Original Length
- Young’s Modulus (E) = Stress / Strain
- Elastic limit, proportional limit, plastic region explained
- Graph: Force vs Extension (linear in elastic region, curved in plastic)
Activities:
- Learners stretch springs and measure extension for different weights
- Record data and draw force-extension graphs
- Calculate spring constant and Young’s modulus from experiment
Experiment: Hooke’s Law Practical
- Materials: Spring, retort stand, weights, metre rule
- Procedure: Hang spring on stand, add weights incrementally, measure extension each time
- Observation: Plot graph of force vs extension
- Conclusion: A straight line indicates elastic behavior; deviation shows limit exceeded
Assessment:
- State Hooke’s Law.
- A spring stretches 0.05 m under a 10 N force. What is the spring constant?
- Differentiate between elastic and plastic deformation.
Homework:
- Complete five Hooke’s Law calculation problems
- Sketch and label a force-extension graph
Expanded Notes:
- Stress and strain are important in understanding structural strength
- Young’s modulus varies between materials; high value = stiff material
- Beyond elastic limit, permanent deformation occurs
Differentiation:
- Visual demonstrations for abstract concepts
- Scaffolded problem-solving for slow learners
- Peer discussion and experiment-led deduction
Teacher’s Reflection:
- Were learners able to accurately take measurements?
- Did students understand how stress and strain relate to material strength?
- Were graphs interpreted correctly?