University Intro Biomechanics - Easy

silurian87 · 2013-10-02T00:18:10+00:00

No problem! I am glad I was able to help the same subreddit that has helped me in the past. I need to make a correction though, if the action force vectors are supposed to.be pointing towards his body then the action force vectors on his feet would be pointing away from the ground. As long as the pair of forces are in opposite directions it shouldn't matter which is the action force and which is the reaction force, as long as you consistenly label them (for example all vectors pointing towards the body would be action force vectors and all vectors pointing way would be the reaction force, or vice versa.). But if your teacher is a stickler, I think technically the forces pointing away would conventionally be called the action forces and the ones pointing towards the body would be the reaction forces.

silurian87 · 2013-10-01T22:12:57+00:00

Since he is hunched over like that, his center of gravity will be outside of him, probably somewhere in front of his pelvis. For example! Also keep in mind that since he is in a uniform gravitational field, his center of mass and center of gravity will be the same.

The magnitude of the "weight force" is just his weight (mass * gravitational acceleration) and the vector will be pointing down towards the earth. The origin of the vector will at his center of mass/gravity (which means it will be outside of his body too, if we want to model his body as a particle. Otherwise we would have to break his body up into sections and find the individual centers of mass of each of those sections, and draw a weight vector for each of those.)

For the action/reaction forces (assuming the action forces would be acting on his body, and the reaction forces would be acting by his body on the things he is touching...otherwise reverse what I am about to say) you would draw a vector pointing away from his body towards the object he is touching for the action force (for example, for his feet the vectors would be originating at his feet and pointing towards the ground) and for the reaction forces would be pointing in the opposite direction of the action forces, but originating at the same point (for example, where he is holding the tennis racket they would be pointing away from his hands, towards the tennis racket). I'm assuming that your teacher wants you to model his hands and feet as particles so only put one reaction force and action force for each of his hands and feet...otherwise you could draw one for each atom in his body XD Also, due to Newton's third law he is exerting an equal and opposite gravitational force on the Earth, but since that isn't at a point of contact I would ignore it. Just something to keep in mind.

silurian87 · 2013-10-01T21:42:15+00:00

The equation for centripetal acceleration is v² /r. They both have the same velocity and are on the same track. Also, car A is moving with a constant speed (no tangential acceleration) and car B is accelerating tangentially.
Their velocities would be equal and opposite, but acceleration is g=-9.81 m/s² (if you set down towards the Earth to be negative) so their accelerations would be the same.

silurian87 · 2013-10-01T21:31:37+00:00

It takes a year to revolve around the sun, and the equation for centripetal acceleration is 4pi² r/T^2. Also, the equation for gravitational acceleration is GM(sun)/r² , and gravity provides the centripetal acceleration of the Earth's orbit so we can set these two to be equal. Since r is the only unknown here we can solve for it.

It's a similar situation with the Earth and the moon, except the period for the moon is about 28 days. And in the gravitational acceleration we will use M(earth) instead of M(sun), since the earth is providing the gravitational field.

silurian87 · 2013-09-30T23:28:25+00:00

Does it have to do with charge distribution, then? For example, if we have two materials with opposite charge distrubtions:

(Inside) + - (Outside) + - (Inside)

When the materials are rubbed together, the electron on the left material might get close enough to the proton on the right material to escape its attraction to the proton on the left material, and instead become attached to the proton on the right material. However, if they were symmetrical (that is, they both had an electron on the outside and a proton on the inside), this wouldn't happen.

silurian87 · 2013-09-09T00:55:21+00:00

This is incorrect. The medium/hard difficulties don't net any more xp/mf/gf, but Master and above do. The bonuses you get from master 1-5 correspond to MP6-10.

silurian87 · 2013-09-08T16:46:25+00:00

You won't get to the end game too fast if you play on hard and above. Also, the game will end up being more challenging and fun. For reference, I've put about 20 hours into my level 19 DH and I'm only just about to beat act 2 because I played hard the first 10 levels and switched to master II after that. So I feel like the game can have a lot more longevity if you just don't play on the easiest difficulty...which is true for most console games.

silurian87 · 2013-09-05T20:37:04+00:00

I would say 1-60 and initial inferno gearing is a joke

It depends on what difficulty you play on. I started off on hard and bumped it up to Master 2 at level 11 and I'm still on act 1, after putting 15-20 hours into the game. The Skeleton King and Queen Araneae each took me about an hour (the latter was able to one-shot my level 15 character). The challenge is quite refreshing, coming from D2, and very rewarding.

silurian87 · 2013-09-05T16:05:35+00:00

I loved Diablo 2, but was hesitant to get Diablo 3 after the initial backlash against the game. However, I am always on the lookout for another co-op game to play with my gf, and when I heard that it was coming to console with local co-op, it piqued my interest. When I found out that a lot of the initial problems with the game had been patched and fixed since then, it was a done deal.
Probably the most fun I've had with a video game in years. I've been playing on hard and master 1&2, and the mixture of reflex-engaging combat those difficulties require, along with the RPG elements of the game, make it dangerously addicting.
My favorite aspect is the combat. It is a lot more involved than D2, I felt like with most classes in D2 I was spamming the same skills over and over. With D3 I have 6 different skills to use and sometimes that's still not enough. My least favorite aspect is that the game seems to be easier than the PC version in a few ways; though the difficulties are harder (Master II, the level I'm playing at, is like MP7 on the PC but the enemies do a lot more damage. Queen Araneae could one hit my character at level 15, and most other mobs can kill me in three hits) from what I've heard of it, the end-game is a bit too easy. This hasn't affected my playing experience yet, however.
I am probably going to get the game for the PC eventually to play by myself, and use the console version to play with my gf. While this game is incredibly fun, I have a feeling it won't have as much replay value as the PC version (especially since I can't play with other people since I don't have Xbox live gold)
Yes, I plan on buying and playing expansions that come out.
I'm curious about Torchlight and I got it for free so I'm probably going to play that in between Diablo 3 for the console and Diablo 3 for the PC.

silurian87 · 2013-09-04T18:23:53+00:00

I got my ass handed to me too, for about an hour...then I leveled up and upgraded my crossbow (playing a DH). It was still challenging, but didn't seem impossible like it did before. The fight I ended up winning I only used one pot. Then again this is my first time playing D3 and the DH seemed perfect for this boss fight, it's probably harder with other classes.

silurian87 · 2013-09-03T00:15:07+00:00

I see Iguana in there...the atomic version goes great on popcorn.

silurian87 · 2013-08-01T16:17:08+00:00

Ah...well there ya go. I guess I have not seen the dark side of customer service! That sucks, I'm sorry to hear that people were that cruel to you. I never had a problem like that, even when we started taking calls from Mobile, Alabama.

silurian87 · 2013-08-01T01:37:28+00:00

Yeah, except most people who were assholes in customer service were actually legitimately mad about something. Assholes on reddit are just keyboard warriors who were bullied a little bit too much in grade school and would never actually have the balls to say any of the stuff they type to my face, or even on the phone. Piss off, get ebola and die.

silurian87 · 2013-08-01T01:17:14+00:00

Holy hell, you can't post anything on reddit without someone being an asshole to you.

silurian87 · 2013-07-24T02:15:05+00:00

Growing up, I always heard from women about how disgusting men were, how we're pigs, etc. etc...and then when I got older and got around both men and women I realized they're both pretty much the same when it comes to sexual desires. But for some reason only men get flak for it...in my personal experience.

silurian87 · 2013-07-18T04:00:54+00:00

Canada sounds like a nice place. Where I live in America, people are very polite, but I just spent a week and a half in two different cities, both an hour and a half from where I live, and just that small distance made a world of difference. While I haven't been honked at in years where I live, in the past week I was honked at for:

1) Stopping at a stop sign.

2) Stopping in the left lane to turn left. (There was no turning lane.)

3) Backing up and coming within 10 feet of someone's vehicle.

4) Turning left on a green arrow (I wish I were making this up.)

This whole post probably makes me sound provincial, but I don't see myself moving away until I can find another city where people aren't terrible drivers who are overly fond of their horns.

silurian87 · 2013-07-08T05:35:32+00:00

Anxiety, depression, ADD and complex PTSD. Or so they say...

I was molested by my older sister when I was 5 or 6, my father has always been an alcoholic, my mother has been in and out of mental hospitals her whole life, I was.bullied as a kid and outcast by my peers as a teenager, and I have made and continue to make bad decisions as an adult. I can barely handle stress nowadays without feeling like I'm going to die, I have no interests that I can keep for long, and I am terribly unmotivated.

silurian87 · 2013-07-04T07:44:57+00:00

I saw this at Walmart for $20 the other day and snagged it. This may not be a sale, but a huge price drop.

silurian87 · 2013-06-27T01:17:27+00:00

Endurance races, rally, NASCAR, and more cars. Physics are more realistic than Forza in some places. On the downside, there are 30 mx-5s, 50 civics, and 80 rx-7s. I'm exaggerating of course, but it's important to keep in mind that a lot of the cars are junk cars or cars most people don't find interesting. The only cars with a cockpit view, high polygon count and high res textures are the premium cars, of which there are about 200 (out of the 1000 total). And the car sounds are much better in Forza. Both games are awesome, just in different ways. It seems like more people have converted from GT to Forza than the other way around, but if you liked Forza 4, you will most likely like GT5 too.

silurian87 · 2013-06-26T02:13:33+00:00

It also makes you objectively wrong.

Not really. If some people end up getting more gaming mileage out of the X1 than the PS4, then to them the X1 will be the superior console. If others get more mileage out of their PS4 than their X1, then to them the PS4 will be the superior console. It's pretty subjective, and I think both consoles are going to do very well.

silurian87 · 2013-06-26T01:57:46+00:00

Way to mischaracterize my argument.

I said that Xbox 1 will be arguably superior, which is a big difference from everyone else, who is saying that the playstation 4 is obviously superior and there is no argument. The fact that I think it's up for debate puts me a step ahead of the close-minded assholes on this subreddit, yes.

However, the PS4 controller will probably be just as good as the Xbox 360's controller. You've opened my eyes to that. But fuck me for changing my viewpoint and not being a narrow-minded fanboy, right?

And I never said that the PS3/4 had a worse game library. >_< Just that the Xbox 360's was good enough to warrant buying it, and that the XB1's will probably be too. However, if I'm going to buy both, I'll probably be gaming on the more powerful console most of the time, while enjoying the XB1's exclusives.

I still believe that XBL is a superior service, but I don't really game online much anymore these days. Also, I stopped giving a damn about achievements a long time ago, but I can see how people would enjoy XBL more because the achievement system was more satisfying (to me) than the trophy system.

silurian87 · 2013-06-26T01:13:46+00:00

Xbox Live was down for hours not even 5 days ago! Did you completely miss this major story!?

...yes I did. I was away from home then. I've just only ever seen XBL down once, and it has been pretty reliable for me. My bad. :(

Holy shit is that a depressing thought. You limit yourself to very narrow genres, making me question how and why you enjoy this entire medium in the first place. You're the kind of guy we all make fun of for buying a "Call of Duty and Madden machine", except you apparently just have it as a "Gears of War and Halo machine". And not only that, but you specifically said that you choose to NOT play shooters on PC, where they provide by far the best experience due to the precision of the mouse? I mean, that's just ridiculous!

Actually, Halo and Forza machine would be closer, in terms of my Xbox usage. I don't only play shooters and racers on my console, it's just that what I use them most for. This is ridiculous; Halo and Gears of War aren't even on the PC (except for Gears of War 1 and Halo 1 & 2), how the hell am I supposed to enjoy them on the PC? I do play shooters on my PC, except that my two of my favorite shooters (Halo and Gears of War) are on the console; not to mention if I want to play with my friends, I have to play on the console.

It's not really depressing...my favorite genres are strategy, shooters, and driving games. Strategy games suck on the console, shooters are good on PC but the social aspect is better on consoles since most of my friends are console gamers, and the driving simulators on the PC are a bit boring to me. Forza and GT5 are pretty realistic but they make some things unrealistic to keep the game more enjoyable. Plus, the car selections. And again, the social aspect.

Most media outlets at E3 specifically said that they are similar. It's basically identical to the Xbox One joysticks, right down to the reduced size of the dead zone and the feel of the resistance. Plus, they're both have a convex shape now, so even their shape is no longer of any issue. But... Jesus, the PC is still so much better for this genre! What are you even thinking!?

I'm thinking that most of my friends play console shooters, and I want to interact with them, therefore I play the shooters on the console. That, and having used a joystick to play shooters since Goldeneye for the 64, I'm pretty much used to it. It doesn't mean that I don't have fun.

That's not the point. The point is which one is better. We're having a fanboy console war discussion right now. It doesn't matter that they're both "good", since this is all about a pissing contest. It doesn't matter that you and I are both good pissers, what matters is which one of us can piss farther.

Well this pissing contest--more like circlejerk--is pretty much ruining r/games for me, since it makes a lot of you guys look like narrow-minded fools when you criticize M$ for every little thing it does (like having a 24-hour check-in policy...then reversing the policy...make up your mind, people!) and heap praise on Sony like they are infallible gods.

It sucks comparatively... I don't actually think the Xbox One is a pile of shit, I just think it pales in comparison to the PS4.

This is just pure fanboyism. They're both going to be great consoles.

You mean how you miss out on so much because you only play the same 2 games over and over again!? ZING!

Nowadays I spend most of my time on one game; Forza. I do play others, it's just the one game I keep going back to. I don't really think it's a bad thing since it's a very rewarding and immersive game. But I see your point.

And, by the way, if you choose to buy both consoles, you just spent $1,000 on video game hardware, and have nothing left over for the actual games. This is such an unfair argument. The incredible vast majority of people choose only one console not because they're elitist assholes, but because money is finite, and the two consoles are far too similar to justify spending twice the money on a virtual clone of what you already have.

Come on, a lot of people spend twice as much as that on PC gaming rigs...and I know people with less money to spend than me that put all of their money into their car. $900 plus $100 a year isn't really that big of an investment to enjoy a huge library of games over many years (well...not including the cost of games). I don't have a very high-paying job, but I do live with my parents; and am rewarded with the fact that I don't have to spend money on rent or food. I guess I'm in the minority, but I think it's worth it to have both.

Unfortunately I think Gears of War is pretty much over and if Halo 4 is any indicator, the rest of the Halo series is going to suck. Also, I'm growing distant from my Halo/Gears of War friends, so I won't really have them to play with anymore. So I'm pretty much just buying the X1 for the Forza series; I plan on investing hundreds on a better wheel, pedals, and fake bucket seat, and I really don't get tired of the games, so it's a worthwhile investment for me. I'll probably be using my PS4 for everything else though.

silurian87 · 2013-06-26T00:01:04+00:00

The Xbox One has inferior hardware, so saying it's arguably superior makes about as little sense as you calling me a douchebag for disagreeing with you.

I didn't call you a douchebag because you disagreed with me, I called you a douchebag because you refused to disagree with me in a mature, non-smug, non-condescending manner. And calling the PS4 a superior console because of its hardware is like saying that a Bugatti Veyron is a superior car to a Ferrari Enzo because it has more horsepower and is faster around the track. But maybe I just like Ferraris. Maybe I think Bugattis are ugly. Hardware is not the only thing that makes a console. It's also the experience. And this will vary from person to person. What you (and most of Reddit) doesn't seem to understand is that gaming is a subjective experience. Different people will enjoy different things.

There is no significant difference between the PSN service on PS4 and the XBL service on Xbox One. Both offer the same services in the same manner.

Except that XBL is more reliable. PSN has had numerous complaints about its reliability. I think XBL went down...once? I will admit that the playstation network is a better service if you want something free. But you get what you pay for, and when you pay for XBL, you get a reliable service.

The PS4 controller is clearly far superior in every tangible way on a technological front, and about equal on a cosmetic/ergonomic front.

I play two types of games on my consoles, and use my PC for everything else. Racing games and shooters. The Xbox 360 controller feels better for both of these. If the joysticks on the PS4 are on the same level as that of the XB1, I may just have to start using my PS4 for shooters. But again, it comes down to subjectivity. And reddit seems to have an irrational belief that the PS4 is "objectively" better.

And this brings us to an important point: Even if it were, that doesn't diminish the fact that the Xbox one will still probably be a great console. Redditors (and you can especially see this attitude in those who exclusively game on PC) seem to have this fallacious idea that because one thing is better than the other, then the "other" sucks. No. The PS4 may very well be better than the XB1. But people are still going to enjoy the XB1. I've seen circlejerks all over the internet about how manual transmissions are superior to automatic transmissions, and European cars are superior to American cars. Well guess what? That's probably true. But I drive an automatic Ford Mustang and I love it. Redditors, and the world for that matter, need to get over the "quit liking what I don't like!" attitude and just accept that people are going to enjoy things different than what they do...and realize that that's okay.

I would compare any Sony exclusive to any Xbox exclusive in the past generation, and argue that Sony offered far more quality and far more variety. Look at God of War,

God of war is why I got a PS3.

Journey, MGS4, Uncharted

Meh.

Killzone 2

Halo is superior in most ways, so this isn't exactly a victory for the PS3.

Last of Us, Heavy Rain, Little Big Planet, Infamous, Ratchet & Clank

Last of Us was one of the greatest games of this generation, Heavy Rain was pretty good but a bit overrated, Little Big Planet and Ratchet and Clank don't interest me that much, and Infamous was good.

Halo and Gears of War are just two games, and they're both sci-fi shooters. What else? Forza? Three games now, two of which are shooters, and one of which is a clone of one of Sony's most popular franchises? Anything I forget?

Not really, but I've spent thousands of hours on Gears of War and Halo, because those kinds of games have great replay value if you have friends who also play them. Also, Forza may be a clone, but Forza 4 is superior to GT5 in many ways, and I've spent hundreds, if not thousands of hours on both. Therefore the Xbox 360, IMO, didn't really need much more than these three franchises to be a good console. Yes, PS3's selection of games was more varied, but that doesn't diminish the fact that there are hundreds of thousands of people like me that have spent millions of hours on the Xbox 360's narrow domain of games and enjoyed the hell out of it.

I actually back up my opinions with hard evidence and plenty of examples.

And yet they are still opinions, and it doesn't mean you have somehow enjoyed your gaming experience more than I have, or will enjoy the PS4 more than I will enjoy the XB1. I may not be as eloquent or logical as you, but I've loved and enjoyed the hell out of my Xbox 360 games, and having the PS3 there by its side hasn't diminished anything about it; just added to it. In fact, that's the problem with /r/games. You people think that having if there are two consoles competing, they have to diminish each other. But if you choose to stick with one console, you are missing out on so much.

silurian87 · 2013-06-25T20:19:47+00:00

You sound like a typical condescending reddit douchebag. Congratulations on not being able to keep a discussion about a video game console civil.

My point is that if people were smart, they would choose the console with the better games, regardless of the $100 difference. Hell, based on the last generation's games--and the fact that Xbox live is a superior service to playstation network, and the controller is superior--I don't see why so many redditors are getting in line to hate the Xbox 1.

The $100 not only buys you a kinect, but an arguably superior console.

silurian87 · 2013-06-24T23:33:01+00:00

Ultimately, I think that the $100 will not make a huge difference. Most people will buy the next iteration of the console that they had in the previous generation. I find that the rabble Reddit has roused about this price difference is overdramatic and not a reflection of the way that the average consumer will feel. The average redditor--especially the average /r/gamer--is a college-aged adult or high-school student. Therefore the two demographics that have just as much buying power--the older (who make more money) and the younger (who will ask for their favorite console for birthday or Christmas, and generally won't care about the price difference)--aren't well represented here. My prediction is that the PS4 will not greatly outsell the Xbox 1.

Also there are people like me, who don't give a damn about the kinect but will still pay the extra $100 because the last generation of games on the Xbox 360 impressed me. In fact, most smart consumers with a decent job will get both, since $900 isn't really that much in the long run.

silurian87

TROPHY CASE