Newtonian world and astrophysics: Thermal physics

Question 1

if one object is hotter than another, what direction does the thermal energy flow?

Answer 1

From the hotter object to the cooler object

Question 2

if 2 objects are in thermal equilibrium, in which direction is the net flow of thermal energy

Answer 2

There is no flow in thermal energy

Question 3

State the zeroth law of thermal dynamics

Answer 3

For any 3 objects, A,B,C if A and B are in thermal equilibrium, and B and C are in thermal equilibrium, then A and C are in thermal equilibrium.

Question 4

What conversion factor is used to convert from Celsius to Kelvin

Answer 4

degrees C +273 = degrees kelvin

Question 5

what conversion factor is used to convert from Kelvin to Celsius

Answer 5

Degrees Kelvin - 273 = degrees Celsius

Question 6

using the kinetic model, describe the structure of a solid

Answer 6

In the kinetic model of matter, solids are composed of particles arranged in a fixed, closely packed, and orderly pattern. These particles vibrate about fixed positions but cannot move freely due to strong interparticle forces, such as covalent, ionic, or metallic bonds. This rigid structure gives solids a definite shape and volume, making them incompressible and unable to flow. The particles have low kinetic energy, which is insufficient to overcome the strong forces holding them in place, resulting in the characteristic rigidity and stability of solids.

Question 7

using the kinetic model, describe the structure of a liquid

Answer 7

In the kinetic model of matter, liquids are composed of closely packed particles that are not fixed in place, allowing them to move past one another. This enables liquids to flow and take the shape of their container while maintaining a fixed volume.

The intermolecular forces in liquids are weaker than in solids, providing cohesion but allowing more particle motion. With greater kinetic energy than solids, liquid particles can move freely but not enough to escape the liquid, balancing fluidity with cohesion and giving liquids their distinctive properties.

Question 8

using the kinetic model, describe the structure of a gas

Answer 8

In the kinetic model of matter, gases consist of widely spaced particles in random motion, moving freely and rapidly in all directions. This allows gases to expand to fill their container and be easily compressed.

The intermolecular forces in gases are negligible due to the large distances between particles, meaning they interact only during collisions. Gas particles have high kinetic energy, which keeps them in constant motion and overcomes any attractive forces, resulting in the characteristic fluidity and compressibility of gases.

Question 9

what factor usually affects density

Answer 9

The spacing between the particles

Question 10

define internal energy

Answer 10

The sum of the randomly distributed kinetic and potential energys of atoms or molecules within th esubstance

Question 11

even if the temperature is at 0K, what quantity can you not reduce to zero in a solid

Answer 11

Potential energy (the substances still have electrostatic potential energy stored between the particles)

Question 12

in general, the hotter a substance, the faster the….

Answer 12

atoms and molecules that make up the substance move

Question 13

When a substance reaches its melting or bowling point, when it is changing phase, what is the thermal energy doing

Answer 13

the thermal energy supplemented after the material reaches its boiling point is used to increase the electrostatic potential of the substance until the phase change is complete

Question 14

What is the electrostatic potential of a Gas

Answer 14

zero because there are negligible electrical forces between atoms or molecules

Question 15

What is the electrostatic potential of a Liquid

Answer 15

The electrostatic forces between atoms and molecules a small negative value. The fact it is negative simply means that energy must be supplied to break the atomic or molecular bonds

Question 16

What is the electrostatic potential of a Solid

Answer 16

The electrostatic forces between atoms or molecules are very large so the electrostatic potential energy has a large negative value

Question 17

Rank in order from smallest to largest the amount of electrostatic potential energy in solids liquids and gasses

Answer 17

solid, liquid, gas

Question 18

Define Specific heat Capacity (SHC)

Answer 18

Specific heat capacity is defined as the energy requires per unit mass to change the temperature of a substance by 1K

Question 19

What is the equation for SHC

Answer 19

E=mc ∆θ
where E is the energy supplied in Joules, m is the mass of the substance and ∆θ is the change in temperature and c is the SHC

Question 20

what is the SHC of water

Answer 20

4200 J Kg^-1 K^-1

Question 21

Describe the Practical used to determine SHC