Changes of State and Heat Transfer (PHYSI)

Flashcards on Changes of State, Heat Transfer, Particle Model, and Fluid Pressure etc.

What happens during melting?

Solid turns into a liquid, internal energy increases.

What happens during freezing?

Liquid turns into a solid, internal energy decreases.

What happens during boiling/evaporation?

Liquid turns into a gas, internal energy increases.

What happens during condensation?

Gas turns to a liquid, internal energy decreases.

What happens during sublimation?

Solid turns directly into a gas, internal energy increases.

What are the key characteristics of a change of state?

A substance is a physical change and can be reversed, not producing a new substance; mass is conserved.

How does density relate to temperature in convection?

Cold fluid is more dense, warm fluid is less dense.

What happens to particles during convection in gases and liquids when heated?

Particles warm up, gas becomes less dense and rises.

How does heat transfer occur through radiation?

A warm or hot object emits infrared radiation as heatwaves, which can be absorbed by another object, heating it up.

What type of surfaces are better absorbers of infrared radiation?

Matte dark surfaces.

What happens to particles in a solid when it gets hotter during conduction?

Particles vibrate more.

Which state of matter is generally better at conducting heat?

Solids.

What type of solid is the best conductor of heat?

Metal.

In what type of substances can convection occur?

Fluids (gases and liquids).

What happens when a fluid is heated during convection?

The particles gain energy and move away from each other, becoming less dense, so they rise.

What is the principle behind how insulation works?

stopping conduction, convection, and radiation to prevent heat loss.

How does a vacuum flask prevent heat transfer?

has a vacuum to stop both conduction and convection and a silvered lining to prevent thermal radiation.

What color objects absorb the most heat?

Dark.

Which type of heat transfer can travel through a vacuum?

Radiation.

What is specific heat capacity?

The amount of energy needed to raise the temperature of 1 kg of a material by 1 degree Celsius.

What is the equation for calculating thermal energy?

E = mcΔT

What is latent heat?

The energy required to change the state of a substance without changing its temperature.

What is the equation for calculating latent heat?

Q = mL

What are the two types of latent heat?

Fusion is solid transforming to liquid and vaporization is liquid transforming to gas.

What is conduction?

Heat/energy is transferred because of molecular contact, particles vibrate against each other.

What is convection?

Energy transfer through density differences within fluids

What is radiation?

Wavelengths of energy emitted from an object.

Describe the particles in a solid.

Fixed position, vibrate, regular structure.

Describe the particles in a liquid.

Able to flow past each other, irregular structure, gaps smaller than particle size.

Describe the particles in a gas.

Widely spaced, not fixed, move freely, random motion, most energy, able to expand.

What is the center of mass?

The point in the object where the whole mass acts.

What does stability depend on?

width of base and height of center of mass; lower height of center of mass = more stable.

What is a lever?

A rigid bar that pivots about a fulcrum; transmits an input motion and force through the lever to a load.

What are gears?

Rotating wheel with teeth that interlock with another wheel, transmit rotational forces, increase/decrease speed.

What is the formula for a moment?

Force x Distance

What is the equation for pressure in fluids?

Pressure = density x gravity x height (p = ρgh)

How does pressure change with depth in a fluid?

Pressure increases with depth.

What is a moment?

Turning effect of a force , act around a pivot , clockwise/anticlockwise

What is the equation for weight?

Mass x gravitational field strength

What is weight?

Force experienced by an object due to gravitational pull of another object (N)