Physics paper 1

• Density is the amount of mass per unit volume
• in a solid particles are

  tightly packed in a regular structure
• in a liquid

  particles are tightly packed but free to move past each other
• in a gas particles are

  spread out and move randomly
• If the object has an irregular shape, the volume can be measured using a displacement can.
• Displacement can

  A) displacement can

  B) measuring cylinder

  
• How to measure the density of a regular solid?

  1. Use a ruler to measure the length (l), width (w) and height (h) of a steel cube.
  2. Place the steel cube on the top pan balance and measure its mass.
  3. Calculate the volume of the cube using (l × w × h).
  4. Use the measurements to calculate the density of the metal.
  5. Use vernier callipers to measure the diameter of the sphere.
  6. Place the metal sphere on the top pan balance and measure its mass.
  7. Calculate the volume of the sphere using 43��(𝑑2)3
  8. Use the measurements to calculate the density of the metal
• how to measure the density of a liquid?

  1. Place the measuring cylinder on the top pan balance and measure its mass.
  2. Pour 50 cm3 of water into the measuring cylinder and measure its new mass.
  3. Subtract the mass in step 1 from the mass in step 2. This is the mass of 50 cm3 of water.
  4. Use the measurements to calculate the density of the water.
• radioactive decay

  The process in which unstable atomic nuclei break apart or change, releasing radiation as they do so.
• alpha


  Subatomic particle with two protons and two neutrons
• beta

  A type of ionising radiation consisting of a single electron.
• gamma


  A type of ionising radiation that is also part of the EM spectrum. It has no mass.
• If the nucleus has too many neutrons, a neutron will turn into a proton and emit a fast-moving electron.
• electromagnetic wave

  A transverse wave caused by oscillations in an electromagnetic field.
• Alpha, Beta And gamma

  
• Density

  The mass per unit volume of a material
• Internal energy of a substance

  • The energy stored by the particles
  • The sum of the total kinetic and potential energies that make up the system
• Heating a substance

  • Transfers energy to the substance
  • Increases the energy of the particles that make up the substance
• Heating a substance

  • Can raise its temperature
  • Can change the state of the substance
• States of matter in order of increasing density

  • Gas
  • Liquid
  • Solid
• Factors determining temperature change of a system

  • Mass of substance being heated
  • Type of material (Specific heat capacity)
  • Energy inputted into the system
• Describe the motion of molecules in a gas

  They are in constant random motion
• Solid

  • Tightly packed in a regular arrangement
  • Particles can only vibrate on the spot
• Liquid

  • Close together, but with an irregular arrangement
  • They can flow over each other
• Equation for temperature change when a substance is heated

  • ΔE = m c Δ𝛉
  • Energy (J), Mass (kg), Specific Heat Capacity (J/kg/°C), Temperature (°C)
• Gas


  • Separated, with no regular arrangement
  • Particles can move freely
• Factor affecting average kinetic energy of gas molecules

  • The temperature of the substance
  • The higher the temperature, the higher the average kinetic energy of the molecules
• What is always conserved when a substance undergoes a change of state
• Specific heat capacity

  The amount of energy needed to increase the temperature of 1kg of a substance by 1°C
• Change of state

  The material can return to having its previous properties if the change is reversed
• Increasing temperature

  Increases the pressure of a gas when held at constant volume
• Chemical change


  The material cannot return to having its previous properties if the change is reversed
• Change of state

  • Internal energy of the substance will be increased or decreased
  • Temperature of the substance will remain constant
• Why pressure increases as temperature increases (at a constant volume)

  1. Kinetic energy of molecules increases

  2. Collisions between molecules becomes more frequent

  3. Greater rate of change of momentum

  4. Greater force and therefore pressure
• Sublimation

  When a solid changes into a gas without passing through a liquid state
• Evaporation


  When a liquid changes into a gas state
• Condensation


  When a gas changes into a liquid state
• Water boils in an open pan

  Some of the water will evaporate and turn into water vapour, leaving the pan and decreasing the mass of the pan. The mass of the whole system however remains constant.
• Specific latent heat


  The amount of energy needed to change the state of 1kg of a substance with no change in temperature
• Bathroom mirror mists up

  1. Hot water evaporates to form water vapour

  2. This water vapour lands on the cooler mirror

  3. The vapour condenses and returns to liquid state on the mirror's surface