Why does kinetic energy increase when temperature increases?
You have cause and effect reversed. If you heat an ideal gas, the kinetic energy of the molecules increases, and statistical mechanics tells us that what we measure as temperature is proportional to the average kinetic energy of the molecules.So how does heating increase the kinetic energy of the molecules? Imagine we put a cylinder of gas on a hot plate. Molecules at the surface of hot plate cause the molecules of the wall of the cylinder to vibrate with more energy, and these in turn cause gas molecules that collide with the wall to leave with more kinetic energy than they came in with.
When we heat a substance does its potential energy increase?
There are only two types of energy in the world.. potential energy and kinetic energy. Potential energy is to do with the ‘relative’ position of particles with respect to each other (also called configuration), and kinetic energy is to do with the ‘time derivative’ of these relative positions. All other energies are derived from these two.If a particle moves, it gains kinetic energy.. but only if it moves relative to other particles. If ‘all’ particles are moving parallel to each other with the same velocity, then no kinetic energy can be detected. If a particle moves with respect to another, the potential energy is changed. A fundamental law of nature is that the change in potential energy due to a change in the separation distance is exactly equal to the change in kinetic energy (energy conservation). When we have many particles we imagine only two at a time and do superposition to find the result for many particles interacting together.When you touch something hot, the vibrating molecules of the hot surface start banging on those of your finger and cause them to move fast. This is what we call temperature. If you move the molecules too fast (too hot) the electrical forces can’t keep the molecules in your finger together and they change/disintegrate (burn). But if the hot substance molecules have internal oscillation and rotation in addition to simple vibration, we do not feel those motions because they they do not readily transmit to our hand and we do not feel it hot. Water absorbs a lot of knocking (heat) before it becomes hot. A piece of metal on the other hand absorbs very little heat and becomes red hot, because its molecules can’t twist and rotate as much.Because of this extra complication in the molecular motion, the relation between heat addition, temperature and potential energy is not a simple straight forward relation. For example, when you heat ice, it ‘contracts’ and changes to water. But on further heating it ‘expands’. Thus for the same heat addition you can have either increase or a decrease. That is why we do not speak of potential energy in relation to heat, but only of ‘internal’ energy. Internal energy includes all types of energy stored in a substance as a result of heat addition. It is given in terms of a factor called the specific heat times the temperature. The specific heat is different for different substances and different temperatures as well!!
Does heat transfer from cold to hot body?
No heat transfers from hot to cold body The first statement of the 2nd law of thermodynamics - heat flows spontaneously from a hot to a cold body - tells us that an ice cube must melt on a hot day, rather than becoming colder.An explanation for this form of the 2nd law can be obtained from Newton's laws and our microscopic description of the nature of temperature. We have already seen that the flow of heat through conduction occurs when fast (hot) atoms collide with slow (cool) atoms, transferring some of their kinetic energy in the process. One might wonder why the fast atoms don't collide with the cool ones and subsequently speed up, thereby gaining kinetic energy as the cool ones lose kinetic energy - this would involve the spontaneous transfer of heat from a cool object to a hot one, in violation of the 2nd law. The answer lies in energy and momentum conservation in a collision - one can show, using these two principles, that in a collision between two objects which conserves energy (called an elastic collision the faster object slows down and the slower object speeds up.It is important to emphasize that this statement of the 2nd law applies to the spontaneous flow of heat from hot to cold. It is possible, of course, to make a cool object in a warm place cooler - this is what a refrigerator does - but this involves the input of some external energy. As such, the flow of heat is not spontaneous in this case.
When a solid is placed in a container and heat is applied, a phase change occurs.?
1. Yes, conversion of solid to liquid is an endothermic reaction and hence energy is absorbed. 2. No, temperature remains constant while phase conversion. 3. No, when heat is given to solid then molecular motion increases and temperature same, as those heat energy are spend in overcoming the intermolecular forces of attraction between molecules. 4. Yes , its true. 5. No, average kinetic energy strictly depends on temperature, but temperature remains constant thus average kinetic energy neither increases or decreases. Edit: At constant pressure (general case) there is NO increase or decrease in temperature in any phase change.
If a pressurized gas is released from a vessel, ice can be seen forming on the outside of the vessel. Why does?
Kumo- is quite correct. Temperature is a measure of the average kinetic energy of the particles. If you compress a gas, what you are doing is forcing the molecules closer together. there are more molecules in a givenn volume; so the kinetic energy increases, and the temperature rises. Let a gas expand, and the molecules move further apart. Although the molecules might still be travelling at the same velocity, and each molecule might still have the same kinetic energy it had in the compressed state, , there are less per volume; so the average kinetic energy is less. The result is that the temperature drops. The drop can be quite dramatic, as in the case of gas escaping from a compressed cylinder. edit: this is how a heat exchanger works: compress a gas, and it heats up. Let the temperature of the compressed gas come to equilibrium with the surroundings. Then let the gas expand (say, INSIDE your refrigerator). It cools down. Then pump the cooled gas outside again and compress it ...