Types of energy
What type of energy is stored in food or fuel?
Chemical energy
What type of energy transformation happens in a light bulb?
Electrical → Light + Heat
Heat always flows from ____ to ____.
Hot to cold
What does 'useful energy' mean?
The energy that performs the intended job
What type of energy does a stretched bow have before firing?
Elastic potential
What type of energy is caused by movement?
Kinetic energy
What is the input energy in a toaster?
Electrical energy
What is the main method of heat transfer in metals?
Conduction
A machine uses 100 J of energy and produces 70 J of useful energy. What is its efficiency?
70%
Which cup loses heat the fastest: metal, foam, or ceramic?
Metal
What type of energy does a stretched rubber band have?
Elastic potential energy
What type of energy transformation happens in a torch?
Chemical → Electrical → Light
Which type of heat transfer occurs through liquids and gases?
Convection
A chainsaw uses 1600 J of chemical energy, producing 850 J heat and 350 J sound. Useful kinetic energy?
400 J
Why do foam cups keep drinks hot longer than metal cups?
Foam is an insulator
Name two examples of potential energy.
Gravitational & Elastic
A fan is plugged in. What are the input and output energies?
Input: Electrical
Output: Kinetic + Sound
Give an example of radiation heat transfer.
Heat from the Sun
Why can no machine be 100% efficient?
Some energy is always lost as heat or sound
Explain why the foam cup shows the slowest drop in temperature.
It traps air and slows conduction/convection
Explain the difference between kinetic and potential energy.
Kinetic = movement; Potential = stored energy
Explain the energy transformations in a hydroelectric power plant.
GPE (water) → Kinetic → Electrical
Explain how a thermos bottle keeps a drink hot.
It reduces conduction, convection, and radiation
Write the formula for efficiency.
Efficiency = (Useful energy ÷ total energy input) × 100
Name one renewable and one non-renewable energy source.
Solar and Coal