making use of energy

Question 1

State three methods of reducing heat loss in a building.

Answer 1

1. Double glazing
2. Loft and wall insulation
3. Thicker walls

Question 2

What is the definition of density? State the relevant equation with units.

Answer 2

The mass per unit volume of a material
⍴=m/v
Density (kg/m³), Mass (kg), Volume (m³)

Question 3

Give the 3 states of matter from lowest to highest density of atoms.

Answer 3

Lowest: Gas
Liquid
Highest: Solid

Question 4

What is always conserved when a substance undergoes a change of state?

Answer 4

Mass

Question 5

State the three different types of energy transfer.

Answer 5

1. Conduction
2. Convection
3. Radiation

Question 6

Explain using a particle model, the process of convection. (Higher)

Answer 6

When heated, fluids expand, making the particles spread out, and making the fluid less dense.
Less dense fluids rise above cooler more dense fluids.
These cooler fluids then heat up and rise upwards, creating a cyclic motion of particles (called a convection current).

Question 7

Explain using a particle model, the process of conduction in a metal. (Higher)

Answer 7

A metal consists of positive ions and free electrons.
As temperature increases, the ions gain kinetic energy and vibrate.
This energy is then passed on via collisions to free electrons which can move throughout the whole metal.
These electrons transfer kinetic energy (again via collisions) to ions further through the metal, increasing their temperature.