Keep the Heat B/Thermodynamics C

[awesome90220]

If I have 2 250 mL, 1 is Pyrex and one is Kimex, but one of them is just a fraction of a cm wider, will i get dqed or point deductions?

[Cheesy Pie]

Dunno but make sure your calculator has battery. Ours died in the event. So we had to do everything the long way.

[Skink]

If I have 2 250 mL, 1 is Pyrex and one is Kimex, but one of them is just a fraction of a cm wider, will i get dqed or point deductions?

This was discussed a page or two ago. Read back.

[awesome90220]

If I have 2 250 mL, 1 is Pyrex and one is Kimex, but one of them is just a fraction of a cm wider, will i get dqed or point deductions?

This was discussed a page or two ago. Read back.

That was for beakers that went up to 200 and 250. Also, I was practicing on the nats test and got lost on 8 and 9, anyone care to explain?
8. The temperature of a gas is a measure of the average kinetic energy of the gas
molecules. Kinetic energy can be found using the formula:
KE = 1/2 mv2
Suppose gas molecules at 200 K have their velocity doubled. By what factor will
the temperature change?
a. 0.5
b. 1.4
c. 2.0
d. 4.0
9. Suppose gas molecules at 200 K have their temperature doubled. By what factor
will the average velocity of the molecules change?
a. 0.5
b. 1.4
c. 2.0
d. 4.0

[AlphaTauri]

8 is D, 9 is B.

8. Say the initial velocity of the gas molecules is x.
Temp_initial ~ 1/2 m x^2

Double x by just dropping in 2x
Temp_new ~ 1/2 m (2x)^2 = 1/2 m 4x^2

The relation for temp_new is greater than temp_initial by a factor of 4, therefore the answer is D.

9. Much the same thing, but we double T instead
T ~ 1/2 m v_initial^2
2T ~ 1/2 m v_new^2

We can actually ignore the 1/2 and m because they stay constant; also, this makes the relations less cluttered (could've done this in the last problem too, now that I think of it). Rewrite to
v_initial ~ sqrt(T)
v_new ~ sqrt(2T) = sqrt(2) * sqrt(T)

Again, the relation for v_new is greater by a factor of sqrt(2) or 1.414..., so the answer is B.

[awesome90220]

8 is D, 9 is B.

8. Say the initial velocity of the gas molecules is x.
Temp_initial ~ 1/2 m x^2

Double x by just dropping in 2x
Temp_new ~ 1/2 m (2x)^2 = 1/2 m 4x^2

The relation for temp_new is greater than temp_initial by a factor of 4, therefore the answer is D.

9. Much the same thing, but we double T instead
T ~ 1/2 m v_initial^2
2T ~ 1/2 m v_new^2

We can actually ignore the 1/2 and m because they stay constant; also, this makes the relations less cluttered (could've done this in the last problem too, now that I think of it). Rewrite to
v_initial ~ sqrt(T)
v_new ~ sqrt(2T) = sqrt(2) * sqrt(T)

Again, the relation for v_new is greater by a factor of sqrt(2) or 1.414..., so the answer is B.

woops, i thought something was something else but im not going to say it because it sounds stupid

[sjwon3789]

Well, I do have 2 250mL. It turns out one of them is Pyrex but the other one is ValueWare. However, the Pyrex beaker says it is a 250mL beaker on the side but it's not labeled up to 250mL...just up to 200mL. The ValueWare beaker, however, goes up to 250mL. What should I do? Also, is ValueWare a valid company to use?

Are they similar sized?

If they are, I would have no problem with them. I have been a KTH ES at 3 Invitationals, and 2 Regionals, but never a State championship.

No, they're not the same size. One's wider than the other one. In other words, I have to find another one, right? If so, is it valid to keep the Pyrex beaker when it says it's a 250mL beaker but only goes up to 200mL? Again, is ValueWare valid company I'm allowed to use?

[GeorgeInNePa]

Well, I do have 2 250mL. It turns out one of them is Pyrex but the other one is ValueWare. However, the Pyrex beaker says it is a 250mL beaker on the side but it's not labeled up to 250mL...just up to 200mL. The ValueWare beaker, however, goes up to 250mL. What should I do? Also, is ValueWare a valid company to use?

Are they similar sized?

If they are, I would have no problem with them. I have been a KTH ES at 3 Invitationals, and 2 Regionals, but never a State championship.

No, they're not the same size. One's wider than the other one. In other words, I have to find another one, right? If so, is it valid to keep the Pyrex beaker when it says it's a 250mL beaker but only goes up to 200mL? Again, is ValueWare valid company I'm allowed to use?

I just looked at my Pyrex (Made in Germany) branded beakers. They are also marked 250ml, but only have graduations up to 200ml (+/-5%).

Go see your school Science or Technology teachers, I'm sure they'll loan you a beaker that matches yours.

[ramcoach]

The 250 ml Pyrex beakers are only graduated up to 200 ml, but that's all you'll need anyway, since Division B is from 100 ml to 200 ml and Division C is from 50 ml to 150 ml plus an additional 50 ml if you want the extra points.

I would make sure that they are the same brand, not just the same size, since different brands may have different glass thickness/composition or different surface areas for the bottom, which could create an advantage for one over the other (intentional or not.) Don't take a chance.

I don't know if failure to comply would be considered a Competition section violation ( lose 4 points) or a Construction section violation (lose 10 points) or if it would be considered a complete violation of the device parameters and thus not be allowed to be used.

[inthewoods]

FAQ is
02/17/2013 - 21:42 Does the "250mL standard, unaltered empty Pyrex (or similar brand name) beaker" have to be made of glass?
Answer: No.

Doesn't this violate the event rule of a standard 250ml "Pyrex" beaker since the definition of Pyrex is A hard heat-resistant type of glass, typically used for ovenware." Does this mean someone can use a plastic beaker?

I think the key words are "or similar brand name". The rules don't say "or similar brand name glass beaker". I don't see any major competitive advantage of using a glass vs. a plastic beaker, and we want this event to be as accessible to everyone as possible, so if you only have plastic beakers available that should be ok.

I just received a response from sonic.org to my concern listed above and the response was "They must be Pyrex glass." I received the email March 11 4:49pm if that is helpful. FAQ has not yet posted the response they gave me. This is very confusing and needs to be addressed. Thank you!!!!!!