Recent content by Crosstalk

That looks correct to me.

That is correct.

I'm not 100% sure on this, but I don't think that the battery's capacity matters.

Lead acid batteries typically have an internal resistance around 20 milliohms.

Try removing all main batteries as well as the backup battery -- and leave it this way for at least 15 minutes (more if you want to be on the safe side). I had my TI-89 lock up once to where waiting, not just pulling all the batteries, was necessary. I hope this helps.

Okay that makes sense -- and I asked because I'd rather not directly answer a homework question for anyone (plus it's against forum rules). You mention a 220v air conditioner. Most home appliances run on AC current (alternating current). Batteries produce DC current (which doesn't alternate)...

The first one sounds like a homework question (which we cannot answer directly), but the second doesn't -- are you asking for schoolwork, or not (if not, then I'll answer much more directly)? For the first question, determining battery life is done entirely through current. A 1 amp-hour...

Could you please explain what you mean by this?

The definition of open set that I was taught in topology* is that a set is open if it is the union of neighborhoods. How is this similar to your statement? This can most easily be answered by relating it to the "union of neighborhoods" definition, as a union of unions of neighborhoods is a...

PVC is not rated for air pressure, so no, it isn't safe (I don't know enough about PVC to tell you if it's worse now than before, though). This is an extremely common mistake among air-cannon makers. The reason is that PVC's failure mode when holding air is to blow up, sending shrapnel and a...

I'll assume you're talking solely about linear motion (i.e. not rotational).* In my understanding, "inertia" is really the property of mass of resisting motion. It is really a result of interpretations of F = ma -- if you don't apply force, the velocity doesn't change (acceleration = 0). If...

I took AP Calculus in high school, (probably Calculus AB, but I'm not sure), and have since been taking math at Oregon State University (OSU for short). At OSU, AP Calculus is equivalent to Math 251 and most of Math 252 (someone who's done AP Calculus may place out of Math 252). Here's the...

Most modern laptop batteries are Lithium-ion batteries, which like to be kept charged. I have had my laptop for a few months (it's about six years old, but it was left unused for a while with a charged battery, and I acquired it in July) and have almost always kept it plugged in while using it...

I'll comment on Facebook -- they really do not like you to use https (https is encrypted, http is not), in my experience. If you just try going to https://www.facebook.com, it seems to try and redirect you back to http://www.facebook.com. The only way I have found to get around this is by...

Going back to the question of whether a random sequence will ever repeat, there are random number generators that do not work with seeds and never repeat. They often use what is called an entropy pool, which is just a big file filled with data that is supposedly random like where you move your...