Lesson Plan

4. Explore the elastic potential store

KS4-18-04

Intent

Lesson Outcomes

  • Define an elastic object
  • Calculate the energy stored in a stretched or compressed object
  • Describe the energy transfers in a bouncing object

National Curriculum

  • Proportionality - for example between weight and mass of an object or between force and extension in a spring - is an important aspect of many models in science
  • Energy changes in a system involving heating, doing work using forces, or doing work using an electric current
  • Calculating the stored energies and energy changes involved

Working Scientifically

  • Use a variety of models such as representational, spatial, descriptive, computational and mathematical to solve problems, make predictions and to develop scientific explanations and understanding of familiar and unfamiliar facts
  • Use SI units
  • Use prefixes and powers of 10 for orders of magnitude
  • Interconvert units

Resources

Resources: Class presentation and handout, 1 cotton spool, 1 toothpick, 1 elastic band, 4 rubber washers and tape or a paperclip. 

Handout: Discuss Hooke and his work on springs. Summarise his contribution to science. Calculations using the elastic Potential Energy Equation. (Including changing units and changing subject of equation). Make a spool racer and observe results. Use this to explore links between potential energy, kinetic energy and elastic potential energy.

Rocket words

  • elastic
  • potential energy
  • energy
  • spring
  • proportional

Implementation

Starter

Determine the factors that affect the EPE stored in a spring. Use the PhET Lab to explore EPE. Apply differing loads and vary the spring constant. The students should be able to grasp the concept of the proportionality of loading to extension. 

Main Teaching

Discuss the engineering concepts of elastic deformation and plastic deformation to explain the limit of proportionality. Use the handout to discuss Hooke's Law and the development of EPE. Ask the students to rearrange the formula given on the first page and solve the EPE problems given on the second page. If time and resources allow, make and test a spool racer. Research old wind-up clocks and write an explanation of their function. The spring contains EPE – provided by the mechanical action of winding – which is released gradually. The clock keeps ticking until all the potential energy has been converted back into movement. Practice rearranging the calculation for EPE.

Today, clockwork torches and radios can be bought.  Where are these items most needed and by whom?

Career Film: This is Cuebong Wong. Cuebong works as a Robotics Research Technologist for National Nuclear Laboratory.

Expert Film: This is Sammy Irving, who works as a Laboratory Technician for National Nuclear Laboratories. Sammy talks about the elastic potential store.

Mission Assignment

Discuss the engineering concepts of elastic deformation and plastic deformation to explain the limit of proportionality. Use the handout to discuss Hooke's law and the development of EPE.

Challenge Task: Why is Hooke's Law and his work on the extension of a spring such an important model in science? Where do you think it is used? Research some of the practical applications. Why do we use models in science?

Impact & Assessment Opportunities

Plenary

Discuss the results from the spool racers challenge. What are the energy stores? How is energy transferred? How is energy dissipated? Use the summative quiz to assess students' learning.