particle model + forces and matter

• Describe the arrangement of particles in a solid

  • are in a regular arrangement
  • vibrate about a fixed position
  • sit very closely together
• Describe the arrangement of particles in a liquid

  • are randomly arranged
  • move around each other
  • sit close together
• Describe the arrangement of particles in a gas

  • are randomly arranged
  • move quickly in all directions
  • are far apart
• What's the formula relating density, mass and volume?

  denisty=mass/volume

  (kg/m$^3$) = (kg) / (m$^3$)
• why do solids, liquid and gases have different densities?

  1. solid: the particles are closely packed together, the given volume is higher.
  2. liquid: particles are less densely packed, number of particles in a given volumes is less than solid
  3. gas: particles are spread out, number of given particles of given volume are low.
• What happens to the mass of an object when it changes state?

  The mass before the change is equal to the mass after the change

  eg. 500kg of a solid melts, it becomes 500kg of liquid
• What is density?

  is a measure of the amount of matter that it comes per unit volume
• What is specific heat capacity?

  Specific heat capacity is the thermal energy that must be transferred to change the temperature of 1 kg of material by 1 °C

  (eg. 4200 J/kg °C, which me ns that 1 kg of water needs 4200 Jof thermal energy to be transferred to raise its temperature by 1 °C)
• What is specific latent heat?

  Specific latent heat is the energy that must be transferred to change 1kg of material from one state of matter to another.
• Explain the difference between specific latent heat and heat capacity

  Specific heat capacity refers to the amount of energy needed to raise the temperature of a substance, while latent heat describes the energy required to change the state of a substance (e.g., melting, boiling) without a temperature change
• describe how the temperature of an object changes with time while being heated or cooled to make it change state

  When a substance is heated, it gains thermal energy. Therefore, its particles move faster and its temperature rises. When a substance is cooled, it loses thermal energy, which causes its particles to move more slowly and its temperature to drop.
• specific latent heat (thermal equation)

  thermal energy for change of state (J) = mass (kg) × specific latent heat (J/kg)
• specific heat capacity (thermal equation)

  change in thermal energy(J) = mass(kg) × specific heat capacity(J/kg °C) change in temperature (°C)
• Explain how changing the temperature of a gas affects the speed of particles

  1. The gas molecules have a greater average of kinetic energy
  2. The gas molecules move faster
  3. More force is exerted on the same area each second
• Explain how the movement of particles cause gas pressure

  The motion of constant, rapid and random motion of gas particles, which collide with the walls of their container, exert a force that is measured as pressure
• how do you convert Celsius to kelvin/kelvin to Celsius?

  Celsius -> Kelvin (+273 to the Celsius temperature)

  Kelvin -> Celsius (-273 from the Kelvin temperature)
• Why is absolute zero significant?

  As a gas is cooled the average speed of its particles falls and its volume gets smaller, at -273 the gas volume shrinks to zero
• What is elastic?

  a body will return to its original shape when the force acting upon its removed
• What is inelastic distortion?

  A body will not return to its original shape when the force acting on it is removed
• What is spring constant?

  The force needed to product an extension of 1 metre
• How do you work out force?

  force=spring constant x extension
• What is the equation for energy transferred?

  energy transferred in stretching = 1/2 x spring constant x (extension)^2