Kinetic Energy, Efficiency, and Elastic Potential Energy
This page delves deeper into specific forms of energy and introduces the concept of energy efficiency in GCSE Physics.
Kinetic Energy:
• Depends on an object's mass and speed
• Calculated using the formula: Kinetic energy = ½ × mass × speed²
Vocabulary: Useful energy is the energy we need and want in a specific situation.
Energy Efficiency:
• Efficiency = Usefulenergytransferred÷Totalenergysupplied × 100
• Wasted energy is transferred to the surroundings through undesired pathways
Highlight: As energy dissipates spreadsout, it becomes less concentrated and less useful.
Machines can be made more efficient by:
• Lubricating parts to reduce friction
• Reducing air resistance
• Minimizing noise production
Elastic Potential Energy:
• Stored in elastic objects when work is done on them
• Calculated using the formula: Elastic potential energy = ½ × spring constant × extension²
Example: A stretched rubber band stores elastic potential energy, which is released when it's allowed to contract.
Electrical Appliances:
• Most energy in homes comes from electricity and gas/oil supplies
• Common uses include heating, lighting, and powering motors
Definition: Power is the rate of energy transfer, calculated as energy transferred divided by time taken.
Highlight: Understanding power and efficiency is crucial for analyzing energy use in everyday electrical appliances and improving their performance in GCSE Physics studies.
