D

#### deleted647690

"What is the speed of a gas particle at 125 C, if it has a speed of 100 m/s at 25 C?"

Okay, so I go to use the equation v2/v1 = square root of T2/T1

I set up V2/100 = square root of 398/298.

__Hm let me make that fraction nicer__v2/100 = square root of 400 over square root of 300

__Square root of 400 is 20. But what is square root of 300? I realize it's between 15 and 20, so I spend a minute or two writing calculations on the side until I realize that 17 is probably the best estimate.__

V2/100 = 20/17

__Let me flip that__100/V2 = 17/20

*What is 17/20? Takes me a second to make it into 85/100.*Alright, so now I have 100=.85V2

*I hate decimals. Let me make that 10,000 = 85V2*Then I have to figure out what 10,000 / 85 is. So I go to long division, and that takes a while.

Finally, I get 117, which seems close to 114, answer D, which is correct.

That whole calculation probably took me 4, 5, maybe 6 minutes. Is there a quicker way to do these? I know that BR has tips, but a lot of the explanations just assume quick calculations that I cannot do in my head. For example, in this question, it says, "The temperature increase is from 298 to 398, which means the temperature is 1.33 times greater."

I wouldn't see something like that, especially in a testing situation. I always do laborious calculations. Also, I have to make a lot of rounding estimations, and sometimes the rounding error builds up so much that the final answer I get is wrong, and all that time I spent figuring it out was wasted.

Also, this is really, really embarrassing, but I still count on my fingers sometimes for some reason. I never seemed to learn how to do quick arithmetic in my head haha. Like 13+6 takes me longer than it should to know.........Or even if I think I know it, I count to make sure I'm not wrong