The Effects Of Temperature

We’re going to learn the effect of temperature on air density through an experiment. Take a mylar balloon and fill it with helium gas and let’s stand inside the house, which, let’s suppose, is currently at 20 degrees Celsius. For anyone who’s used to Fahrenheit, this is around 70 degrees Fahrenheit. So, it’s nice and warm in the house. Now what’s happening inside this balloon, we can see it’s nice and stiff, and it’s because of the warm temperature in the house. It’s causing all the helium air molecules and the gas molecules to bump around. They become really energetic, and when they’re really energetic, they bounce around a lot, and the gas expands. That’s what happens in warm temperatures, our gases expand, and that increases the pressure that it’s exerting. Now we’re going to step outside because, let’s say, in really cold weather, and we’re going to figure out what will happen. 

Let’s say it’s around minus 15 degrees Celsius, and if we look at the balloon, it starts getting saggy, so what’s happening is that the cold temperature is reducing the kinetic energy for that helium gas. The molecules are cold,  they’re shivering, and they’re just moving slower, so the air pressure is much lower, and it’s not pushing out on the balloon. So, what’s happening is just a change in temperature that’s decreasing kinetic energy, and the air molecules are slowing down. They’re pushing less on the outer of the balloon, and it’s deflating, and that’s because it’s super cold out.

If we step back inside, we can just watch. Just thanks to a change in temperature, we’ll see that it’s going to start to go back up and increase, and the balloon will be coming back to life because our molecules are regaining their kinetic energy by moving around, bouncing together, and it’s all back to normal all thanks to air pressure.

Let’s understand this by looking at an experiment. You will find that there are two vessels, vessel number one and vessel number two. Now in the first vessel, you find that the molecules are moving slowly because it is not being heated, so it is at a lower temperature.

In the case of the second vessel, we find that after being heated, the molecules are moving about very rapidly, and since it is being heated, it is at a higher temperature. 

Now, what is happening? In the case of the first vessel, when the molecules are not being heated, the molecules are moving about slowly, and in the second case, where it is being heated, the molecules are in rapid motion. Do you recall what we studied about Sound? Sound travels through a medium through molecular vibrations. Now, if the molecules are moving about slowly and if the molecules are moving about very fast, do you think it has an effect on the speed of sound?

We can say that when the temperature of the vessel is low, the molecules inside the vessel have low kinetic energy. And when the temperature of the vessel is high, the molecules in the vessel have higher kinetic energy. So, if they have higher kinetic energy and higher speed, and in this case, if they have lower kinetic energy and a low speed, how do you think it affects the speed of sound?

Just as we learned, if the temperature is increased, the kinetic energy or the to and fro vibration of the molecules increases. And if the temperature is decreased, then the kinetic energy or the to and fro vibration of the molecules decreases.

Now, do you think air being hot or air being cold has an effect on the velocity of sound?

We just learned that when the temperature of the medium increases, the kinetic energy of the molecules in the medium increases. This means they rapidly vibrate about their mean position, and what was sound? Sound travelled through a medium through vibratory disturbances through molecular vibrations. So the molecular vibrations increase the sound velocity in the medium will also increase. Now when the temperature of the medium is decreased, the vibrations of the molecules or the kinetic energy of the molecules is decreasing, and since the molecular to and fro vibrations are decreasing, the sound velocity in that medium will also decrease, and since velocity is directly proportional to wavelength the same is the case in that type. We learned that temperature is one of the influencing factors of the velocity of sound.

Conclusion- 

When the temperature changes, there are many other changes also happening in regard to different fields. For example, there is enzymatic action; in biochemistry, it’s something different. So if you are interested in temperature and its associative effects, you can look into these topics.