Energy Flashcards
To revise the energy topic (paper 1)
What is a system?
an object or group of objects
Describe the energy changes when a ball is thrown upwards
Kinetic energy into GPE and thermal
Describe the energy changes when an object hits an obstacle
Kinetic into Thermal and sound
Describe the energy changes in a torch
Chemical into electrical into thermal and light
State the equation and all units for kinetic energy
kinetic energy (J) = 0.5 × mass (kg) × speed Squared (m/s)
State the equation and all units for GPE
g.p.e. (J) = mass (kg) × gravitational field strength(N/kg) × height (m)
Define specific heat capacity
the amount of energy required to raise the temperature of one kilogram of the substance by one degree Celsius.
State the units for specific heat capacity
J/kg °C
Define Power
Rate at which energy is transferred into a new form
State the equation with all units for Power.
Power (W) = energy (J)/ time (s)
Define 1 W
An energy transfer of 1 joule per second
State the conservation of energy
Energy can be transferred usefully, stored or dissipated, but cannot be created or destroyed.
Define thermal conductivity
How well a material can insulate. The higher the thermal conductivity of a material the higher the rate of energy transfer by conduction across the material.
How can heat loss from a building be minimised?
Using thicker walls and materials with a lower thermal conductivity
Define efficiency
How effective a device is at converting its input energy into a useful output form of energy
