* Pressure *
1) what other ways can the pressure of a gas be changed?
* Internal Energy *
2) A cup of hot tea is poured from a teapot, and a swimming pool if filled with cold water.
a) Which one has a higher internal energy?
b) Which has a higher average of kinetic energy?
* Transfer of Heat *
- Conduction -
a) Why are the liquids and gases good insulators?
b) Why is the snow coverage the same on all roofs?
c)Does a 'warm' blanket provide you with heat?why?
d) Why can you stick your hand into a oven for several seconds without harm, whereas you would never touch the metal inside oven even for a second?
- Convection -
a) Why an you hold your fingers beside the candle flame without harm, but not above the flame?
* 1st Law of Thermodynamics *
a) if 10 J of energy is added to a system that does 4 J of external work, by how much will the internal energy of the system be raised?
>> please help me!!
1) The pressure of a gas can be changed by altering the volume, temperature, or number of gas molecules.
- Changing the volume: Increasing the volume will decrease the pressure, while decreasing the volume will increase the pressure. This is known as Boyle's Law.
- Changing the temperature: Increasing the temperature will increase the pressure, while decreasing the temperature will decrease the pressure. This is known as Charles's Law.
- Changing the number of gas molecules: Increasing the number of gas molecules will increase the pressure, while decreasing the number of gas molecules will decrease the pressure. This is known as Avogadro's Law.
2)
a) The cup of hot tea has a higher internal energy because it has a higher temperature. Internal energy is the sum of the potential and kinetic energies of the particles within a system, and temperature is a measure of the average kinetic energy of the particles. Therefore, the higher the temperature, the higher the internal energy.
b) The swimming pool with cold water has a higher average kinetic energy because temperature is directly related to the average kinetic energy of particles. Cold water has lower temperature than hot tea, which means that its particles have lower average kinetic energy.
Transfer of Heat:
- Conduction:
a) Liquids and gases are good insulators because their particles are further apart and have weaker intermolecular forces compared to solids. This makes it more difficult for heat to be conducted through them.
b) Snow coverage is the same on all roofs because snow has insulating properties. It prevents heat from escaping through the roof and keeps the lower layers of snow from melting.
c) A "warm" blanket provides you with heat by trapping your body heat through conduction. When you come in contact with the blanket, the heat from your body is transferred to the blanket through direct contact and then retained within the blanket, keeping you warm.
d) In an oven, the metal surfaces can reach very high temperatures, while the air inside the oven is typically at a lower temperature. This is due to the difference in conductivity between metals and air. Metals are good conductors of heat, so they quickly transfer heat to your hand, resulting in burns or harm. On the other hand, the air inside the oven has lower conductivity, so it takes longer for the heat to transfer to your hand, allowing you to withdraw it before burning.
- Convection:
a) You can hold your fingers beside the candle flame without harm because convection currents rise upwards from the flame, carrying the heat away. By placing your fingers beside the flame, you are positioned in an area where the convection currents are not strong enough to transfer significant heat to your fingers. However, if you hold your fingers directly above the flame, the upward convection currents will bring the heat directly to your fingers, causing harm.
1st Law of Thermodynamics:
a) The first law of thermodynamics states that the change in internal energy of a system is equal to the heat added to the system minus the work done by the system. In this case, if 10 J of energy is added to the system and it does 4 J of external work, then the internal energy of the system will be raised by 6 J. This can be calculated using the formula: Change in Internal Energy = Heat Added - Work Done. In this case, it would be 10 J - 4 J = 6 J.