Section 4: Energy

Question 1

Know the equation for efficiency

Answer 1

Efficiency = useful energy output / total energy input

Question 2

Describe how energy transfer may take place by conduction, convection and radiation

Answer 2

Conduction is when energy is passed from one particle to another via contact..
Convection is when particles with energy rise, the space they leave is filled by other particles.
Radiation is when heat istransferredas infra red waves.

Question 3

Explain the role of convection in everyday phenomena

Answer 3

Convection is helpful as it distributes heat energy. This is useful in many situations, for example, a radiator in one place will be able to heat a whole room, as hot air will rise away from it creating a current of cool air to be heated.

Question 4

Know and use the relationship between work, force and distance moved in the direction of the force:

Answer 4

work done = force × distance moved

Question 5

Understand the relationship between work done and energy transferred

Answer 5

work done is equal to energy transferred

Question 6

Know and use the equation for potential energy

Answer 6

gravitational potential energy = mass × g × height

Question 7

Know and use the equation for Kinetic Energy

Answer 7

kinetic energy = 0.5 × mass × speed2

Question 8

Describe power in terms of work

Answer 8

Power is the rate of work, the to figures are exactly the same

Question 9

Use the relationship between power, work done and time taken:

Answer 9

power = work done / time taken

Question 10

Understand that energy is conserved

Answer 10

Energy cannot be created or destroyed it can only be changed from one form to another.