During my course of teaching of elasticity ,i teach about the energy stored in the stretch string.One of the example is a sling in which when rubber string is stretched elasticpotential energy get stored and when it is released it converts into kinetic energy. WORK DONE AND ELASTIC ENERGY Let us take the example of a wire. Suppose the original length of the wire is L, When not deformed, there are no internal forces. As the length of the wire increase from L to L + DL, internal forces increase from 0 to F. Suppose at any instant when the length is (L +x), the internal force is Fx. The work done to further increase the length through dx is Fxdx, hence total work done
W=Fxdx =EA/L x dxSo the total work done is W = ½ EA/L (DL)2W = ½ F (DL)Thus, the elastic energy per unit volume is given by-U = W/AL = ½ stress ´ strain(1)The above results is true for all types of stress and strain.(2)The work done per unit volume or the elastic energy per unit volume is given by half the product of stress an…
This article is By Rhett allen
Refrigeration: the process of decreasing the temperature of some thing (my definition). Air conditioning (AC) can be a form of refrigeration.
There are several ways to reduce the temperature of things – like a person or a beer. The history and physics of cooling things can be quite interesting. I’m not a historian, so I am only going to speculate on the timeline of events in the life of refrigeration. However, I feel comfortable explaining the physics in each method.
Humans Discover Sweat
Humans just can’t help it. Sometimes they get hot. But alas! Humans have a built in cooling systems. It’s called sweat. In order to understand how it works, maybe we should first look at temperature. You can measure the temperature in Celsius (°C) or Fahrenheit (°F), but what are you actually measuring?
If I were to give a simple definition of temperature, I would say that it is a measure of the average motion energy of the particles that make up that object. T…
Yesterday i found this interesting problem . Have fun in doing this.
On April 15 an airplane takes off at 4 : 40 p.m from Belem. Brazil bound
for Villamil, Ecuador (in the Galapagos). The plane lands at 8 : 40 p.m.
Villamil local time. The sun sets at 6 : 15 p.m. in Belem (local time), and 7 :
06 p.m. in Villamil (local time). At what time during the flight do the
airplane passengers see the sun set?