 Okay, let's do another example of how you use a specific heat capacity to work out the energy needed for a temperature change. Let's look at paying cricket. Let's imagine we have a cricket oval somewhere, and there are two people, each of whom has a cricket ball. Now, one person runs along like crazy, and then bowls the ball at a world record speed, and the other person just sticks the ball in their pocket. Now, which of these people is going to add more energy to the cricket ball? Now, sounds like a stupid question to ask, of course a fast bowl of wood, but let's do the numbers, and of course the answer will turn out to be a little surprising. So, let's look at the first person. They are fast bowling. So, how fast is a fast bowl cricket ball? It turns out it's about 40 meters per second. It's about the speed of a world record bowl cricket ball. How much is a cricket ball weigh? Well, a cricket ball is supposed to have a mass of around 160 grams, which is 0.16 kilograms. So, the kinetic energy is one half mv squared. So, that's a half times 0.16 times 40 squared, which comes out as 128 joules. So, that's the energy you've given to a cricket ball when you are one of the world's greatest fast bowlers, and you throw a vicious fast bowl down the pitch. Now, what happens to the second person when they put the ball in their pocket? When the ball sits in your pocket, it will warm up because of the contact with your leg. Let's say it warms up by one degree. I think it will warm up by more than that, but let's be conserved and say, since in your pocket it warms up by one degree. So, how much energy now? In this case, the change in energy of the ball is given by the mass times the specific heat capacity times the change in temperature. Now, cricket balls are mostly made of cork, and it turns out cork has a specific heat capacity of about 20, 50 joules per kilogram. Change in temperature goes up by one degree. The mass is 0.16, so that comes out as 0.16 times 20, 50 times 1, which is equal to 328 joules. So, that's rather surprising. If you want to give more energy to cricket ball, put it in your pocket. Even for one degree change in temperature, you get double the energy of the world as fast as fast bowler. Well, if you think about it this kind, it makes sense. We said that the atoms in your air room temperature are going around at well over 1,000 kilometers an hour. So, when you add in the temperature, the speeds are enormous. Far faster. No one can bowl at that sort of speeds. So, yes, they actually use thermal energy. The energy of all these random motions and chemical bonds stretching and rotations and things in their typical cricket ball vastly exceeds the energy you can give it by bowling. Strange but true.