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Phys Particle Model
Physics Pacticle Mod
Question | Answer |
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The density of a material is defined by what equation? | density= mass / volume |
What can the particle model be used to explain? | The different states of matter and differences in density |
How do you phrase why different states of matter have different densities? | 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 |
How do you measure object density? | Regular - measure dimensions and weight. Irregular - displacement of water from a displacement can (which has been filled and allowed to drain fully from the spout) |
Why does mass not change when state changes? | Throughout all of these changes, the number of particles has not changed, just their spacing and arrangement. As a result, the total mass has not changed. |
Why are physical changes different to chemical changes? | The material recovers its original properties if the change is reversed. |
What is internal energy? | The total kinetic energy and potential energy of all the particles (atoms and molecules) that make up a system. |
How is energy stored inside a system? | Energy is stored inside a system by the particles (atoms and molecules) that make up the system. This is called internal energy. |
Why does heating change the energy stored within a system? | Heating changes the energy stored within the system by increasing the energy of the particles that make up the system. This either raises the temperature of the system or produces a change of state. |
What is the equation relating to specific heat capacity? | Change in thermal energy = mass × specific heat capacity × temperature change |
What is specific heat capacity measured in? | J/Kg'C |
What is the specific heat capacity of a substance? | The amount of energy required to raise the temperature of one kilogram of the substance by one degree Celsius. |
What is the energy needed for a substance to change state called? | Latent heat |
When a change of state occurs, the energy supplied changes what? | The energy stored (internal energy), because the potential energy increases, but not the temperature (kinetic energy). |
What is the specific latent heat of a substance? | The amount of energy required to change the state of one kilogram of the substance with no change in temperature. |
What unit is used for specific latent heat? | j/kg |
What is the equation relating to specific latent heat? | energy for a change of state = mass × specific latent heat |
What is specific latent heat of fusion? | Change of state from solid to liquid |
What is specific latent heat of vaporisation? | Change of state from liquid to vapour |
What is the difference between specific heat capacity and specific latent heat? | Specific heat = energy needed to change one kilogram of a material by 1°C, while latent heat = energy needed to change the state of one kilogram of material. |
What does changing gas temperature do when held at constant volume? | Changing the temperature of a gas, held at constant volume, changes the pressure exerted by the gas |
Why is the relationship between temperature and pressure? | When the temperature is increased, the gas particles move faster and the collisions become harder and more frequent. This means that the pressure also increases |
What direction is the net force of a gas? | Pressure produces a net force at right angles to the wall of the gas container (or any surface). |
Why does increasing the volume of a container decrease pressure? | If the volume increases the distance the molecules must travel to strike the walls increases and they hit the walls less often thus decreasing the pressure |
For a fixed mass of gas held at a constant temperature, what equation links pressure and volume? | pressure × volume = constant |
What is work? | Work is the transfer of energy by a force. |
What does doing work on a gas do? | Doing work on a gas increases the internal energy of the gas and can cause an increase in the temperature of the gas |
How, in a given situation eg a bicycle pump, does doing work on an enclosed gas leads to an increase in temperature of the gas? | Doing work on the gas increases the internal energy, and because no change of state is taking place, that means that potential energy is not increasing, so the kinetic energy must increase instead, increasing the temperature |
On a temperature time graph | The diagonal parts are increasing kinetic energy. The flat parts are increasing potential energy. The flat parts are changes of state. |
Fix for specific heat capacity | J/kgC |
Why can environmental issues not be fixed easily despite being known about? | Political, social, ethical, or economic considerations |