Classical Physics

Hi, I have a handful of questions about collisions and sound. Thanks for stopping by. How fast does kinetic energy transfer between two objects in a perfectly elastic collision? Does a perfectly elastic collision ever occur outside of a lab? What happens to the kinetic energy that is lost in an inelastic collision? Now, I dont know if these questions should be in another thread in another forum, so I will post them here as well. They are questions about sound. I know that the speed of sound varies in different mediums. Does sound have kinetic energy, since it is a compression wave? Could it be said that as a medium increases in hardness/stiffness/rigidity, …

Hi, Could someone please explain to me how satellites orbit the earth? I know about gravity providing the centrepetal force and all that, but I still don't quite get it. If one were to launch say, an apple or something horizontally from some peak with a high velocity, how come it'll fall straight back down in projectile motion? How come some things orbit the earth when launched whereas some things don't? Is there a like minimum distance or velocity that an object has to be launched with in order for it to orbit and not fall straight back down? Thx

Hi i thought of making a motor out of perminent magnets and i cant find any flaws in my plans, BUT i need to know if 1. are there magnets out there that are strong enough to make it worth while 2. has anybody done anything like this before plz help if you can

Hi, Im trying to answer a question that I have no idea about. Its quite urgent and I was wondering if anybody could help me out, the question I am trying to solve is... If two objects ( the same weight, but different mass) fall in water, which is most likely to sink in fastest. The one with the higher mass or the one with the least mass??? I would really appreciate it if you could post something back with an answer or help!!!! Thanks =] Aimee

So I am a person sitting on a chair that has wheels. Now, the question is - can I push the chair when I am sitting on the chair and have nothing to push against? [other than the chair]? Note that I have no contact whatsoever with the floor. From experience, I know I can. So why? Whenever i try to push against the chair, according to Newton's 3rd Law, each force produces an equal and opposite force. So as I push against the chair, I exert a force, and it exerts an equal and opposite force on me. But I move along with the chair, so I must exert a second force on the chair, which is in the opposite direction as the direction of acceleration of the chair. (a) <---…

Hi, I'm in gr. 11 physics, for a project, we have to build some kind of jumper. The "winner" is one that jumps the highest with the best weight/height ratio. Compressed gas, rockets and propellers are not allowed. Anything else is fine, like springs/elastics, I think magnets are allowed but I can't think of any way to make the whole system jump. It has to jump, not fly. I really can't think of any, and my idea is really complicated and I have no idea how I'm even going to guild it. Any ideas? Thanks.

Is it posable to use some type of sail, as so many science fiction books have invisioned, to propell an object through space away from a star? It seems possable since our atmosphere is blown egg-shaped by it, but I am not sure so I came to ask.

I really tried to use the search but frustratingly couldn't find a thread answering my question. On the moon (About 1/3rd of Earth Gravity (Irrelevant to out discussion so I wont mention it again) and no atmosphere) a hammer apparently reaches the ground when dropped from a set height at the same time as a feather. I understand how air resistance effects terminal velocity. And how air makes things of different shapes fall differently, so I would expect the 1KG of feathers in a weightless bag with all the air sucked out to fall at the same rate as the one 1KG hammer. However I am having trouble grasping how the 1 single small light feather can reach the ground …

As I read the Wikipedia article on torque, found here, I notice that the SI unit of torque is the newton-meter, not the Joule. Why is that? The base units for torque come out to the same as work or energy (kgm^2/s^2), and it's even calulated with the same math as work (force times length), so why is it not refered to as a Joule?

I've thought of this new concept of gravity that I'm not sure if it is correct. I was wondering does acceleration affect gravity more than mass. See everything with gravity so far that we know of has some type of rotation going on. So does that mean that it is not mass that carries gravity but the force of acceleration (which also depends on the mass of the object to have a strong enough force to accelerate).

Warning: MATH ALERT Here may be a fun problem for you to think about and solve... In 1989, Shirley Muldowney set a new record for the fastest 1/4 mile by a wheel-driven car. If I told you that the coefficient of static friction between her tires and the road was mu = 3.34, what was her best possible time? Cheers, w=f[z] Footnote: Her record has been broken since, but I'm too lazy to look up the new number and owner of that number. Edit: Would someone be kind enough to tell me how to get LaTeX to work here. For example, $\mu=...$ doesn't seem to work. Thanks!

Here is a little question; Let's say you are driving along in your car on a cold-autumn day. You have a passenger in the center of the back seat that is holding a helium-filled balloon in front of them by the string. You make a sharp left turn around a bend in the road. Which way does the balloon move relative to the car? (Justify your answer.) Cheers, w=f[z] P.S. I'm still really new here, so my apologies if this has already been discussed.

I am 100% sure that unless otherwise a pressure is exerted all the bodies in universe move in a definite circular or elliptical motion in contradictory to the present theory. That motion is directly or indirectly proportional to the mass of the matter. Light even has the same circular or elliptical motion. Then many stars that we see might be only duplicate image due to the circular motion of light. Also the gravitation is nothing but occurred due to this circular motion of matters. Tomorrow science will prove that….Good luck to the future guys, though I may not be there……. Why gravitation fails to explain many things still today. When an apple is in the high altitud…

Hi everyone, Here is one more to go along with the balloon and 1/4 mile questions while I'm at it. Let's say you are standing near a cliff. You crack open a bottle of beer and immediately let go of the bottle over the cliff (imagine it remains upright throughout the fall and no beer spills during the fall). (I know, I know... what a waste of beer - even in the interest of science....) So the question is this; which way do the bubbles move relative to the bottle during the fall? Cheers (literally ) w=f[z] P.S. Again, newbie here. So sorry if this has already been discussed.

Hello, does anyone know how to do this question? Gear A (radius = 150mm, mass= 4kg and radius of gyration = 100mm) and gear B(radius = 450mm, mass= 10kg and radius of gyration= 300mm) rotate about their respective centrers. A constant clockwise torque of 0.75Nm is applied to the gear A. neglecting bearing friction torque, determine the angular acceleration of each gear and the tangential contact forces between the gears.

How much energy in Kilowatts are present in a spinning mass weighing 2 tons (4,400 lbs) and spinning at 8,000 RPMs?

I know that gravity depends upon mass but what if the mass was spread out? For instance, Jupiter has a great amount of mass and therefore very powerful gravity but what if you flattened Jupiter into a great ring around the sun? Would any part of that ring retain the full gravitational force of the planet equal to when the planet was one round ball? Or would the spread out mass greatly affect the gravitational pull of the ring? I don’t know a lot about gravity so I have no idea. Need some help if you can. Thanks!!!

Hi all, I have been involved in this ridiculous debate which has raged on for quite some time, and so I would like to pick your collective brains. As the title suggests, the debate is about how much energy would be required to turn a 1 Ton block of set construction concrete back in to particles of a 100 microns across. I don't know if this is something which can be calculated in KWH (killowatt hours), but this is a unit of energy that I understand (probably because I see it every three months when I get my electric bill). I realise this probably sounds a bit silly, but I could not think of any where else to go in order to get an answer. Thanking you all in…

I have a question. If a rollercoaster is going down a slope and I need to work out the gravitational potentail energy can I just use the formula GPE = Mass *gravity*height I know I can use that for when something is just falling but is it different when it's going down a slope? If so can you please tell me what formula i should use or how I can calculate the GPE? All replies are appreciated.

The suns rayes are considered to be basicly paralell when they aproach the earth because of the earth's grate distance from the sun. If so, why then on a broken clowdy day the sun rays as they punch through the holes in the clowds are far fron paralell ?

Imagine we have 2 equal masses, one at rest and the other coming towards it at a velocity v. If we take Kinetic energy to be conserved during the collision, and therefore that the collision is elastic we can analyse it in 2 different ways and yield different conclusions. For example, if we look at what I will call the 1 dimensional case: [math]mv=mv_1+mv_2[/math] Where [math]v_1[/math] and [math]v_2[/math] represent the velocities of both masses after the collision. As the masses are equal, we can say: [math]v=v_1+v_2[/math] Also as energy is conserved: [math]\frac{1}{2}mv^2=\frac{1}{2}mv_1^2+\frac{1}{2}mv_2^2[/math] Therefore: [math](v_1+v_2)^2=v_1^2+…

Now wait. Hear me out first before jumping to conclusions. We often take for granted the thought that gravity is a force, but if it were a force, it wouldn't be constant because if it were constant, an object of less mass would accelerate more rapidly than an object of greater mass due to inverse proportionality. Force is mass times accelertion, so if the force were constant, and the mass decreased, then the acceleration must increase. But that's not the case. All free-falling objects in a vacuum affected by the same source of gravity accelerate uniformly. The only way these two problems could be solved is if you were to say that gravity is not constant, but t…

Hello, I'm a new member. If I am posting in the wrong forum please help by telling me where to post on this topic. I'm interested in doing some science projects with my son. We've seen some interesting things with magnets. I want to be able to answer his questions about some of them. Some of the questions are: 1. Can magnets be shielded so they do not attract nearby metals and/or other magnets? The way I described it was like helping Superman out by putting the kryptonite in a lead box so it can't harm him. 2. Do magnets weaken over time? If so how long does it take to happen? 3. If I take a magnet and force its north pole next to another magn…

http://www.msnbc.msn.com/id/18334489/ there is a video too, showing Stephen Hawking floating in zero-gee a related Reuters story: http://www.msnbc.msn.com/id/18330938/

Would like to know if any of you have ever wondered when clouds are seen to be stationary with reference to the ground, could it be that: a) the winds are moving the clouds at the same speed as the earth's rotation? ~OR~ b) is it that when the earth spins, the whole atmosphere, including the clouds, moves along with it? And if this is the case, what causes the clouds to move along with the Earth? Is it due to gravity? All help are greatly appreciated. Thanks in advance.