2009 B

[sxk1693]

Looks like taking 3 science tests in 3 days paid off.
288: 112,104,72.

I have a bunch of questions though:
Bio: 3.????????????????????????? What!!! How is this C. Can someone explain. I chose B. Nucleotides make up DNA.

Chem: 36. I put D. 38. What's a Lewis acid.

Physics: 41 Guessingt skills failed me. 45????????????????????? What is this? 25000 has 2 SIG FIGS. HOW IS IT E: Indeterminate. can someone explain??? I want a 296.
46. <TROLL FACE> It seems so simple, but no matter what I do, I keep getting A, not D.
55. I just don't know how to answer this one.
56-60.
Can someone pls explain 56-60.

[sxk1693]

Ok, so for number 45, there has got to be an answer key mistake. I looked it up on google, and it said 2222222222222.

[darksaber21]

For number three, that is the order from largest to smallest. The genome is all of the genetic information, which is encoded in DNA, which contains chromosomes, which is made up of genes, and nucleotides are the smallest units.

[darksaber21]

For number 36, catalysts never provides energy for the process. A catalyst only allows a different pathway for the reaction to take place, one where the energy required is less than normal, hence why catalysts lower the activation energy for reactions.

For number 38, Lewis acids and bases deal with electrons rather than protons, so think the opposite. Acids donate protons (hydrogen ions), so they accept electron pairs so that way they can become bases.

[darksaber21]

You would need to revisit your significant figure rules for number 45. Based on the rules, 25000 could have anywhere from 2 to 5 significant figures. Why? Because we are uncertain how accurate the results truly are. We could have rounded to tens place or the hundreds place and end up with 25000. If the number had a decimal point, then we know that it is 5 significant figures because we know that the data was taken to the ones place.

Remember, significant figures depends on how accurate your data is.

[darksaber21]

For 55, we know that impulse is involved as there was contact for a length of time, and there was a change in velocity due to the force inflicted during that time. As such:

[unparseable or potentially dangerous latex formula]


Using your kinematic equations, you should obtain:
(velocity right before impact) [unparseable or potentially dangerous latex formula]
(velocity right before impact) [unparseable or potentially dangerous latex formula]

So, [unparseable or potentially dangerous latex formula]

Reason why Δv is higher is because the initial velocity is in the negative direction, and the force caused the velocity not only to slow down but to speed up in the opposite direction.

So, now we can determine the force:
[unparseable or potentially dangerous latex formula]


We are not done yet. What we found was the average force on the ball. When the ball strikes the floor, there are two forces at that point in time: the normal force and the force of gravity. The sum of these forces equal the average force that we found. At this point, you could just circle E as that is the only answer larger than 3.4, but I'm going to just show the set-up anyway.

-------

Edit: I'm adding this here in case anyone will become confused:

[unparseable or potentially dangerous latex formula]

We are solving for N, the normal force placed on the ball that actually caused it to change direction

-------
So:
[unparseable or potentially dangerous latex formula]

[darksaber21]

Number 46:

[unparseable or potentially dangerous latex formula] [unparseable or potentially dangerous latex formula]


Remember to match your units up. You know you did something wrong if your units don't match.

[sxk1693]

[darksaber21]

Those examples you gave all have a decimal in it. 25000 doesn't, so it hard to tell the accuracy of the number.

You could write 25000, for example, on the calculator test if it is the correct answer, and it will be considered three significant figures then. It is due to the fact that the number could have anywhere from 2 to 5 sig figs.

[101dalmatians]

[darksaber21]

What? You don't understand? I could make a post talking about everything that has to do with significant figures.

Only if everyone doesn't mind, and if I have the time for that.

[101dalmatians]

[darksaber21]

I really was not taught significant figures that much, nor was it imposed on me that much. It is just something I researched on my own and experimented with and taught myself (especially with the AP Chemistry test I took last year).

And I am willing to support the key in this case (as much as I want it wrong sometimes :p).

[sxk1693]

[101dalmatians]