Science nerds please help me answer this!!!

Well I'm in love with science but I can't help you if this is for school. It would be cheating!

KE = 3/2kT

Well I'm in love with science but I can't help you if this is for school. It would be cheating!

Caught out! haha :smooched:

Mastering Physics or Chemistry homework?

LOL. I LOVE THIS SITE!

Boyle's Law, perfect gas laws P1V1/T1 = P2V2/T2

It takes work the air or gas to be "forced" into the balloon. Due to the "work" as the gas enters the balloon, the pressure increases, the balloon expands, and the temperature goes up.

Have you noticed that in the winter, the air pressure in the tires of your car goes down. The temperature of the air in the tires gets colder, the pressure decreases, and so does the volume. So you have to add "air" to raise the pressure in your tires.

Boyle's Law.

Boyle's law assumes that the number of atoms remains the same, which is not the case here. It is of course the case for the tires.

emergencytennis, doesn't volume change as well? I'd agree with you if the container had a fixed volume, but in this case it is not obvious that temperature will change.

Since the question assumes that the temperature does increase I assumed that some of the kinetic energy goes into increasing the balloon's volume and the rest contributes to temperature gain.

Not even thinking about the temperature of the air blown from the experimenter's lungs compared with the ambient temperature. Just going with particle theory.

PV=nRT ideal gas law..
The temperature of the gas is proportional to the average kinetic energy of the molecules

As the balloon fills with fluid the balloon expands. As the balloon expands, it exerts pressure (compression) on the fluid which causes friction between particles. Thus the temperature increase.

Except, this does not hold true with a fluid. The bonds between particles in a fluid preclude compression, or else the brakes in your car wouldn't work.

In the view of physics, air is a fluid (fluid dynamics, hydrodynamics, aerodynamics, etc). That is the capacity in which I was using the term.

Boyle's law assumes that the number of atoms remains the same, which is not the case here. It is of course the case for the tires.

emergencytennis, doesn't volume change as well? I'd agree with you if the container had a fixed volume, but in this case it is not obvious that temperature will change.

Since the question assumes that the temperature does increase I assumed that some of the kinetic energy goes into increasing the balloon's volume and the rest contributes to temperature gain.

Not even thinking about the temperature of the air blown from the experimenter's lungs compared with the ambient temperature. Just going with particle theory.

Anyone mentioning Boyle's Law only gets partial credit. Not your fault, teachers probably taught you wrong. Boyle's law has no temperature component. Charles law would have been a slightly better answer.

Anyone mentioning the ideal gas law (which is NOT Boyle's law) gets partial credit. It's correct to use it but it isn't sufficient.

As gas is pumped into the balloon both pressure and volume are increasing and balancing the atmospheric prressure and the elastic ballon properties. The n in the equation is certainly increasing. If temperature is increasing its due to the elasticity (and hysteresis) of the balloon wall in which the volume change is not just the offset of the increase in n. The walls exert an increase pressure, ergo temp increase.
Pascal's law tells us that the pressure is the same in balloon for the gas.
Laplace's law tells us more about the wall tension based on the diameter of the balloon.

King of the mountain.

Edit: but the question is about kinetic energy. The puppies analogy is correct. My above answer, as well as any answer using Boyle's law, would be wrong since it does not address kinetic energy.

Eta: misuse of apostrophe.

As you force air into the balloon the pressure inside it increases. What is happening is that you are jamming more and more air particles into the available space.

Now, imagine putting puppies into a playpen. The more puppies you put in, the more they interact with each other and bump the playpen. If it is full of puppies they can't avoid collisions.

This is exactly what is happening inside the balloon. There are more and more air particles in the space and they collide a lot more frequently, both with the balloon and with each other. Each collision releases energy in the form of heat. The kinetic energy of the particles is transferred to heat energy by the collisions.

Now to make sure you understand, tell me why, if I can heat up air by squeezing it into a balloon with my lungs, why doesn't a block of steel heat up if I squeeze it with my hand?

This! :bigsmile: