We can solve the problem by using the first law of thermodynamics:
where
is the variation of internal energy of the system
Q is the heat absorbed by the system
W is the work done by the system
In this problem, the heat absorbed by the system is Q=+44 J, and the increase in internal energy is
. So we can rearrange the equation to calculate the work done:
and the work is positive, which means that it is done by the system on the surrounding.
Convection occurs through heat transfer due to a difference in density in the fluids.
Consider a pot of water being heated. The water in the pot gets heated rises ,it provides energy for the particles in the water to move and thus the water expands which results in the density of the water becoming less. These particles rise up till the top of the pot owing to the property of very less density of the particles.
Then after some time, it cools down which results in increase of the density of the particles. The heavier denser particles sink to the bottom and is once again heated and rises and this process continues unless all the water particles in the pot are heated and warmed.This transfer of energy by the movement of particles cause convection.
During the day the heat surface above the earth exposed to the sun's rays is heated. This rise in temperature,decreases the density of the air and the warm air rises.
This air cools down and becomes denser. This dense cool air sink back and forces the warm air to rise again.
This transfer of movement of particles causes convection. This cycle is the cause of winds and thus energy is transferred through the atmosphere.
Answer:
Ultraviolet rays from sun are very harmful from skin and can cause sunburn and skin diseases especially ultraviolet B rays.<em> A sunscreen lotion act as a protection barrier on the skin that restrict the direct contact of UV rays with skin and filter the harmful rays to enter the skin. </em>
Radiotherapy is a medical therapy use to treat cancer. <em>Radiotherapy commonly uses x-rays and gamma rays because they are high-energy particles or waves that kills or destroys the cancer cells.</em>
Answer:
3.72 kJ
Explanation:
QH = 6.45 kJ
TH = 520 K
Tc = 300 K
Qc = ?
By use of Carnot's theorem
Qc / QH = Tc / TH
Qc / 6.45 = 300 / 520
Qc = 3.72 kJ
Answer and Explanation:
In optics, a CoC(Circle of Confusion) is defined the minimum cross section of a paraxial bundle of rays made by a lens which is sphero-cylindrical type and can be viewed as an optical spot, which do not converge perfectly at the focus while a point source is being imaged due to spherical aberration.
The Circle of Confusion is also referred to as circle of indistinctness or a blur spot
