Introduction
Energy is the capacity to do work. It exists in various forms such as potential energy, kinetic energy, mechanical energy, heat energy, and electrical energy. In nature and in machines, energy continuously changes from one form to another. The Law of Conservation of Energy states that energy can neither be created nor destroyed; it can only be transformed from one form to another.
This working model demonstrates the conservation of energy using a falling weight, string, pulley, and rotating wheel. The model clearly shows how gravitational potential energy gets converted into kinetic and rotational energy, and how the same energy causes motion without being lost, only transformed.
Aim of the Project
To demonstrate the Law of Conservation of Energy using a simple mechanical system involving:
- Gravitational potential energy
- Kinetic energy
- Rotational mechanical energy
Materials Required
- Cardboard or thermocol base
- Four cardboard or wooden sticks (pillars)
- Cardboard strip for the top frame
- Thread or string
- Plastic or cardboard wheel (CD, tape roll, or handmade disc)
- Wooden skewer or metal rod (axle)
- Small weight (nut, stone, or washer)
- Glue (Fevicol or hot glue)
- Cutter and scissors
- Paint and chart paper (for decoration and labeling)
Construction / How to Make the Model
Step 1: Making the Base
Take a rectangular piece of thick cardboard or thermocol as the base. Cover it with colored paper to give a neat appearance. This base will support the entire structure.
Step 2: Making the Vertical Stand
Fix four vertical pillars on the base using glue. These pillars should be strong and of equal height. Attach a cardboard strip on the top to connect the pillars, forming a stable frame like a gate.
Step 3: Fixing the Wheel (Pulley/Flywheel)
Make a small hole at the center of the wheel (CD or disc). Insert a wooden skewer or rod through it so that the wheel can rotate freely. Fix this rod horizontally to the top frame using supports, ensuring the wheel spins smoothly.
Step 4: Attaching the String and Weight
Tie one end of the string to the axle or rim of the wheel. Attach a small weight to the other end of the string. Make sure the string is wound neatly around the wheel.
Step 5: Final Adjustments
Check that:
- The wheel rotates freely
- The string unwinds smoothly
- The weight can move up and down without obstruction
Decorate the model and label parts such as wheel, string, weight, and energy transformation stages.
Working of the Model
When the weight is lifted to a height, it possesses gravitational potential energy. As the weight is released, it starts falling due to gravity. During this fall:
- Potential energy decreases
- The falling weight gains kinetic energy
- This kinetic energy causes the wheel to rotate
- The rotating wheel stores rotational mechanical energy
When the weight reaches the bottom, the wheel continues rotating for some time due to inertia. If the system is designed properly, the rotation can even lift the weight again slightly, showing energy transfer in the reverse direction.
Thus, energy is continuously changing forms but is not destroyed.
Scientific Principle / Concept
Law of Conservation of Energy
Energy can neither be created nor destroyed; it can only be converted from one form to another.
Energy Transformations in This Model
- Gravitational Potential Energy
Stored when the weight is raised to a height. - Kinetic Energy
Produced when the weight starts falling. - Rotational Mechanical Energy
Stored in the rotating wheel. - Minor Energy Losses
Some energy is converted into heat and sound due to friction and air resistance, but the total energy remains conserved.
Mathematical Explanation (Optional for Viva)
- Potential Energy = mgh
- Kinetic Energy = ½mv²
As height decreases, speed increases, proving energy conversion.
Why the Model Demonstrates Conservation of Energy
- No external energy is added after releasing the weight
- Motion occurs only due to energy transformation
- Energy keeps changing form but total energy remains constant
- Even energy losses are accounted for as heat and sound
Applications in Real Life
- Hydroelectric power plants
- Elevators and lifts
- Mechanical clocks
- Flywheels in engines
- Pulley systems
- Roller coasters
Advantages of This Model
- Easy and low-cost
- Uses simple materials
- Clear visual demonstration
- Suitable for school exhibitions
- Easy to explain in viva
Conclusion
This working model successfully demonstrates the Law of Conservation of Energy by showing the continuous transformation of energy from one form to another. The falling weight, rotating wheel, and motion clearly prove that energy is not lost but converted. Such models help students understand abstract scientific laws through practical observation and real-life examples.