Which would show an example of how physical changes are reversible? cutting a gold bar in two pieces and then putting the pieces
next to each other burning a match and then relighting it melting tin and then cooling it into a mold combining sodium and chlorine to make the new material of table salt
Melting tin and then cooling it into a mold is an example of reversible physical changes.
<u>Explanation:</u>
When an object undergoes a change in size, state, or shape and not in their chemical compositions referred to as physical change. But chemical change occurs as a result of the change in substances composition. It also forms a new one by the combination/ breakage of one or more objects.
In the case of making gold cube into two pieces, there is no possibility of getting the original state again even the physical change happens. Match burning and relighting and sodium plus chlorine forming table salt show chemical change. But in tin melting and cooling it to form mold is the physical change i.e changes in state(liquid to solid) and are reversible too.
Energy is the ability to do work so I would say that thermal or heat energy is a type of work. Don’t know if this will work but that’s what I would put.
Stage fear is one that a person experiences when he feels exposed to what others are going to say. This feeling is characterized by the fear of public speaking. Some common causes are large crowds or stress associated with an important presentation where people can stutter and do a poor job.
