P1 Energy

Question 1

What is the law of energy?

Answer 1

Energy cannot be created or destroyed it can only be stored or transferred.

Question 2

Give the eight energy stores.

Answer 2

1) Thermal energy
2) Kinetic energy
3) Gravitational potential energy
4) Elastic potential energy
5) Chemical energy
6) Magnetic energy
7) Electrostatic energy
8) Nuclear energy

Question 3

Give the four transfers of energy and when they are done.

Answer 3

1) Mechanically (when a force is doing work).
2) Electrically (work done by moving charges).
3) Heating
4) Radiation (light and sound)

Question 4

What is a system?

Answer 4

A system is a single object or group of objects performing a certain task.

Question 5

What is a closed system?

Answer 5

A system where neither matter nor energy can enter or leave.

Question 6

What is the transfer of energy in the system of water boiling in a kettle?

Answer 6

Energy is transferred electrically to the thermal energy store of the kettle’s heating element, which transfers energy by heating to the water’s thermal energy store.

Question 7

Work done is just another way of saying (blank)

Answer 7

Energy transfered.

Question 8

Give the equation for Kinetic energy, say what each symbol stands for and the units for each thing.

Answer 8

E=1/2 x m x v^2
E= Kinetic Energy which is measured in joules (J)
m= mass which is measured in kilograms (kg)
v= velocity which is measured in meters per second (m/s)

Question 9

Give the equation for Gravitational Potential energy, say what each symbol stands for and the units used to measure each thing.

Answer 9

E=m x g x h
m= mass measured in kilograms (kg)
g= Gravitational field strength (N/kg)
h= height which is measured in meters (m)

Question 10

What is an example of a process that would result in energy being gained in an objects kinetic energy store.

Answer 10

Any movement on an object for example the movement of a body part of vehicle.

Question 11

What is an example of a process that would result in energy being gained in an objects Gravitational potential energy store.

Answer 11

The lifting/raising of an object in a gravitational field off the ground.

Question 12

What is an example of a process that would result in energy being gained in an objects Elastic potential energy store.

Answer 12

The stretching or squashing of an object.

Question 13

Give the equation for the change in thermal energy, what each symbol means and the units to measure each thing in the equation.

Answer 13

ΔE=m x c x Δθ

ΔE= change in thermal energy which is measured in (

Question 14

Give the equation for the change in thermal energy, what each symbol means and the units to measure each thing in the equation.

Answer 14

ΔE=m x c x Δθ
ΔE= change in thermal energy which is measured in (J)
m= mass which is measured in Kilograms (kg)
Δθ= temperature change which is measured in degrees Celsius

Question 15

Define specific heat capacity

Answer 15

The amount of energy needed to heat 1 kg of a substance by 1 degrees.

Question 16

What is the specific heat capacity of water.

Answer 16

4200 J/kg (degrees Celsius)

Question 17

Give the 5 stages of the Specific heat capacity required practical.

Answer 17

1) Get a block of a solid material with two holes in it.
2) Measured the mass of the block then wrap in an insulating layer to reduce energy transferred to the surroundings. Insert the thermometer and heater.
3) Measure the initial temperature of the block and set the volts of the power supply to 10V. Turn on the power supply and start a stopwatch.
4) As the block heats up take readings of the temperature from the thermometer and current from the ammeter in the circuit every minute for 10 minutes. You should find that the current through the circuit does not change as the block heats up.
5) When you’ve collected enough readings turn off the power supply. Use -P= V x I- to calculate the how much energy has been transferred to the heater. To calculate how much energy has been transferred to the heater at each temperature reading using the formulae E= P x t where t is time in seconds since the experiment began.

Question 18

Define the term dissipated

Answer 18

It is when some energy is not transferred usefully into the store you want it to go.

Question 19

Describe the energy transfer of a closed system (a flask filled with soup) when a cold spoon is placed in it. The lid is still sealed.

Answer 19

Energy is transferred from the thermal energy store of the soup to the useless thermal energy store of the spoon.

Question 20

What is power?

Answer 20

Power is the rate of energy transfer, or the rate of doing work.

Question 21

What is power measured in and what does this equal?

Answer 21

Power is measured in watts. 1 W= 1 Joule of energy transferred per second.

Question 22

Give the equation for power, state what each symbol represents and what the unit is for each thing.

Answer 22

P= E/T 
P= Power, measured in watts (W)
E= Energy transferred, measured in joules (J)
T= Time, measured in seconds (s)

Question 23

Give the conservation of energy principle.

Answer 23

• Energy can be transferred, stored or dissipate but it can never be created or destroyed. `

Question 24

What is conduction?

Answer 24

• Conduction is the process where vibrating particles transfer energy to neighboring particles.

Question 25

If a material had a high thermal conductivity what would this mean?

Answer 25

• This would mean that the material would transfer energy between its particles quickly.

Question 26

What is convection?

Answer 26

• Convection is where energetic particles move away from hotter to cooler regions.

Question 27

What happens to the density of a gas or liquid and why?

Answer 27

• When you heat a gas or a liquid the density decreases.

- This is because the particles move faster and the space between the particles increases.

Question 28

What happens to the less dense region of a gas or liquid after it is heated?

Answer 28

• The warmer, less dense region will rise above the denser and cooler region and a convection current will be created if there is a constant heat source.