Energy

Question 1

What are all the energy stores

Answer 1

Thermal, kinetic, gravitational potential, elastic potential, chemical, magnetic, electrostatic, nuclear

Question 2

What is work done in physics

Answer 2

Another way of saying transfer of energy
- work can be done when current flows or by a force moving an object

Question 3

For falling objects the rule for the transfer of energy is

Answer 3

Energy lost from the gpe store = energy gained in the kinetic energy store

Question 4

Kinetic energy

Answer 4

• anything moving has energy in its kinetic energy store
• energy is transferred to this store when an object speeds up, and is transferred away when an object slows down
• the energy in a kinetic store depends on both speed and mass; the greater it’s mass and the faster it’s going, the more kinetic energy it has

Question 5

Kinetic energy formula

Answer 5

E = 1/2mv^2
Kinetic energy (j) = 1\2 x mass (kj) x speed squared (m/s) squared

Question 6

Gravitational potential energy

Answer 6

• lifting an object in a gravitational field requires work, this causes a transfer of energy to the gpe store of the object
• the higher the object is lifted, more energy is transferred to its gpe store
• the greater the object’s mass, height and the gravitational field the strength, the more energy in the objects gpe store

Question 7

Gravitational potential energy formula

Answer 7

E = mgh
Gpe (j) = mass (kg) x gravitational field strength (N/kg) x height (m)

Question 8

Elastic potential energy

Answer 8

• stretching or squashing an object can transfer energy to its elastic potential energy store, so long as the limit of proportionality has not been exceeded

Question 9

Elastic potential energy formula

Answer 9

E = 1/2ke^2
Elastic potential energy (j) = 1/2 x spring constant (N/m) x extension squared (m)

Question 10

Specific heat capacity

Answer 10

• some materials need more thermal energy for them to increase their temperature
• specific heat capacity: the amount of energy needs to raise the temperature of 1 kg of substance by 1degree celcius

Question 11

Formula involving specific heat capacity

Answer 11

Change in thermal energy (j) = mass (kg) x specific heat capacity (j/kg’C) x temperature change (‘C)