Energy Flashcards
(38 cards)
What is a system in physics?
An object or group of objects that can transfer energy between stores.
What happens when a system changes?
Energy is transferred between different stores, often dissipated as heat or sound.
Give an example of energy transfer when a ball hits a wall.
Kinetic energy of the ball β sound and thermal energy at the wall.
Give an example of energy transfer when a vehicle slows down.
Kinetic energy β thermal energy due to friction.
What is the formula for kinetic energy?
πΈπ = 1/2 ππ£Β²
What are the units in the kinetic energy equation?
Mass = kg, Speed = m/s, Energy = J
What is the formula for elastic potential energy?
πΈπ = 1/2 ππΒ²
What does each symbol represent in πΈπ = 1/2 ππΒ²?
π = spring constant (N/m), π = extension (m), πΈπ = energy in J
What is the formula for gravitational potential energy?
πΈπ = ππβ
What is the value of gravity on Earth?
π = 9.8 N/kg
What is specific heat capacity?
The energy required to raise the temperature of 1 kg of a substance by 1Β°C.
What is the formula for change in thermal energy?
ΞπΈ = ππΞπ
What is power in physics?
The rate of energy transfer or work done.
What are the two formulas for power?
π = πΈ/π‘
π = π/π‘
What is the unit of power?
Watt (W)
What does 1 Watt represent?
1 joule of energy transferred per second.
How can we compare two motorsβ power?
The one that does the same work faster is more powerful.
What is meant by energy dissipation?
Energy spread to surroundings, usually as thermal energy β less useful.
State the law of conservation of energy.
Energy cannot be created or destroyed, only transferred, stored or dissipated.
How does lubrication reduce energy loss?
Reduces friction, so less energy is dissipated as heat.
How does thermal insulation reduce energy loss?
Reduces heat transfer, keeping energy within the system.
What does thermal conductivity measure?
How easily heat is transferred through a material.
How do materials with high thermal conductivity affect energy transfer?
Increase the rate of heat transfer.
How can we reduce energy transfer in buildings?
Use thick walls with low thermal conductivity.
