Physics

(1) Suppose that a runner on a straight track covers a distance of 1 mile in exactly 4min. what was its average velocity in (i) mih-1 (iii) cms-1 (ii) fts-1 (iv) kmh-1 (2) A projectile is shoot at an angle of 60o to the horizontal with an initial speed of 225ms-1. Determine the time of flight horizontal range and maximum height attained by the projectile. (take g = 9.8ms-2) (3a) A bullet of mass 10g traveling horizontal at a speed of 100 ms-1 embeds itself in a block of woods mass 990g suspended by a string so that it can swing freely. Find the vertical height through which block rises. (bi) Ex…

I'm training to be a professional wrestler right now. Earlier today, my trainer complained about the room we were in being "the hottest room on earth." I told him, "No, the hottest room on earth is in Great Britain. It's literally hotter than the center of the Sun." After about thirty seconds of "Are you serious" "Yes I am" back and forth, he finally said "I don't believe it." I know you guys know I'm right, so can you give me a credible link (meaning no wikipedia, more like a University) providing documentation of this room's existence so I can email it to him? I'd look it up myself, but I'd need the name of the room to do that, which I don't have. Thanks ah…

Hi, I have a question regarding light, specifically artificial light. Please forgive me I am not a physics guru by any means and my terminology may be completely wrong, but hopefully someone will be able understand what I am trying to ask. First, the only way I know how to ask is in basic terms, I know that there is much more to it than that. So, I am asking in terms that I feel that I understand. Ok here it goes. Lets assume you have two lights, one light is 5000k and the other is 2700k. Considering that both lights are 23 watts each. Which light has the energy to penetrate...lets say a plant canopy better? The blue or red? Or another another way to a…

We just learned what these are today in math. I get the concept of it, but im not sure of its application. Lets say you have a equation with a negative inside a square root. You turn it into an i. Im not sure how this would help you. I havn't taken calculas yet so maybe i'll learn it then?

This has been in the back of my mind a while and just wanted to throw it out there to hopefully get some support for my answer to a problem. The place I work at regularly receives shipments of hydrogen gas. One of the truck drivers insisted that after he unloads the hydrogen into our storage tanks that his truck is actually heavier. I disagreed with him. I think that he imagines that hydrogen just magically floats and that he doesn't understand that hydrogen has mass (weight) but is buoyant in the heavier gases of our atmosphere. I reasoned with him that he is taking a large gas cylinder and taking some of the mass (hydrogen) out of it while the cylinder still d…

My knowledge of Physics does not extend far beyond K10 or the UK GCSE. However, I read that buckyballs (C60 =bucminsterfullerene) forced into diffraction slits caused an interference pattern typical of waves, demonstrating, once again, the duality of matter. http://www.quantum.univie.ac.at/research/matterwave/c60/index.html#Motivation If this is the case, and we become Spike Milligan silly here, can you fire a series of cats through an appropriate slit diameter and get the same pattern?

I am wondering if anyone on this forum knows of or can suggest chemicals that are solar reactive? I mean reactive in the way that they can polarize or become sensitive to magnetic influence?

I just wondered. Get two locations that are a fair distance apart but where there is also a fair height differance between them. For example cliffs on the south of england to a beach in France. Create a system similar to that of cable carts or ski lifts but not powered by anything, so it is like a piece of wire connected at both ends to a large pulley and in a loop. Containers that people could stand in would be placed at intervals around the loop. One end is higher and there are heavy carts around the loop but nothing would move anywhere for now. Water could then inexpensively be added to the top end, ether at a type of movement cart or just in an area in the car…

A new technology which will help provide personal vehicles after oil is on the way. http://www.worldchanging.com/archives/002435.html I quote : "The Japanese tech giant announced today a new generation lithium-ion battery technology which can be recharged to 80% in one minute, with total recharge taking a few minutes more. " Electric cars currently under development are stated to have a range up to 350 kms. Imagine an electric car that has a range that is a large fraction of that - say 250 km - and can be recharged in less than 10 minutes. You drive on your holiday vacation, for 200km. At that stage, you pull into a recharge spot, which might be a ca…

I'm in need of a table or formula (empirical fit) of the conversion of ethanol/water mixtures weight percentage to volume percentage, and back. I know how to calculate the theoretical conversion (ideal mixtures), but I doubt that ethanol/water can be considered ideal. I also found an online conversion tool, but I'd really prefer to have all data neatly in a table. Does anyone have a reference for me? p.s. If the volume percentage is as simple as taking the volume of the pure ethanol and the volume of the pure water, and then dividing the ethanol volume by the sum of the water and ethanol, then I am just a nut. (My results for that don't seem to correspond with th…

If the earths rotation sped up gradually, then would the centripital force eventually overcome gravity and lead to zero-gravity on earth?

I've bought one of these electric fly zappers in the shape of a small tennis racquet, it runs off 2 AA batteries and virtually vapourizes small flies so what's the current of one of these things? I understand the voltage produced from the 2x1.5V batteries is 1500V. G56

I`v been considering one of Newtons laws in relation to Rocket science, specifically Water rockets and was wondering if I would get more thrust if the water being thrown out the back was heavier, such as a saturated salt soln. but then I figured that the rocket and the water it was carrying would Also weigh more and thus it would cancel out any advantage it may give me. so I went to opposite extreme and thought why does it need it water at all? can`t I just use the air alone. but then I figured that would work only if the bottle itself weighed nothing. so somewhere in between Must be an optimum "fuel" density, does anyone know what that would be for using a 2…

Are photons the only particles that don't exert a gravitational force on other particles?

Hello everyone. While this isn't for homework perse, I've got a simple question that has been frustratingly difficult to dredge out the answer/formulae to. How can I calculate the time it takes an object to rise and fall from elevation A to elevation B at initial upward speed of X units per second and gravity of Y units per second? My Google-fu has failed me, so I'd be appreciative of a working method for this. {Edit: And I've apparently posted this in the wrong forum. Go me. Blah.}

Hello guys, I know how to use the right hand palm rule. But I'm bit confused with the direction of the magnetic field.Let say current is into the page in a straight wire and then magnetic field is going on a circular loop and can be worked out accordingly with grip rule. But when I do the palm rule I don't know which way the magnetic field should be. There are so many places (I mean the which part of the circular loop that is perpendicular I choose.)Any help would be appreciated. Thanks!!

I remember being quite excited by this charging mat when it first came out. apparently you could recharge any device after first plugging the mat into the mains. You could then automatically charge up any electronic device that contained rechargeable batteries. However, what has happened since and how does it work? Because I need one! http://news.bbc.co.uk/1/hi/technology/2861987.stm

Hi everyone i have a question. If i were to get a jar and put a magnet on the lid, bottom, and one suspended between the two, if i made a vacuum in the jar (get all of the air out) and had the suspended magnet spin would it spin for ever? (or at least a very long time!)

Ok look I don't really know to much about this but I need to ask someone what they think and maybe some answers will spawn. Ok I was watching a show on Apollo 11 and when they took of it made the flag spin round and round. My idea is well this could prove some thing. Well if the flag is still moving it proves Newton's first law of motion because the flag wouldn't be acted upon by another force which forces it to continue to move. But if the flag isn't moving it would mean either A. Newton's Laws of Motion are flawed. or B. There is some kind of force acting upon the flag which brings it to a stop. This has been on my mind for a while and I didn't know who to ask. Remember…

Hello Edtharan, I cannot spell linear ha! I enjoyed your answer to the hoverboard question back in February so I thought I would make you my first contact and post on this website. I'm creative but have no formal education however I have considered the basics of gyroscopic forces,angular momentun and procession, conservation of momentum, righthand rule ect... My area of interst is angular momentun converted to linear momentum as result of collisions in order for momentum to be conserved, in general, so, since velocity is a vector, momentum is also a vector, pointing in the same direction as the velocity, of course. It turns out experimentally that in any collision bet…

There is something I've always been curious about regarding high and low temperatures, namely whether or not hot cancels out cold. Let's say you are inside a freezer that is at a constant temperature of -70 degrees Celsius, also inside this freezer is a burner that is at a constant temperature of +70 degrees Celsius. Now, for this thought experiment we will assume that both the freezer and the burner are kept at their temperatures of +- 70 degrees Celsius. Let's say you were to put your hand on the burner, my question is whether the burner would burn you or if the two temperatures would cancel each other out.

It is so damn hot. And i probably dont have any right to cry, relative to Arizonans, Nevadans, or anywhere else where its similarly sweltering. I cant help but think this heat ought to be doing something. There must be some way to harvest energy from this heat, is there a system like this in use? Maybe it would just be solar energy, i dont even know how that works though. What im thinking of is like fields of metal rods, painted the blackest black absorbing all the heat, making energy, and then routing it back to me, running an AC. All this heat can be put to work, i know it. Tell me how so i can make one.

Hi All, This might seem a little unusual, but I'm a social scientist who has always had a keen interest in physics. Having just completed my PhD I now have time to devote this pursuit. I was wondering if anyone might suggest some texts that I could use for self study. I took undergraduate courses in classical and quantum mechanics, as well as, electromagnetic theory. I'm hoping to learn physics at the graduate level (to include classical mechanics, electromagnetism, quantum, and statistical mechanics). I have a fairly rigorous background in mathematics (functional analysis, dynamical systems, real analysis, etc.); however, I would also be interested in getting feedbac…

Just a simple question that occurred to me today: if the universe is expanding, why does the distance between the earth and the sun remain unchanged?

My Physics knowledge is not good but can someone answer these questions. Space is not a perfect vacuum - does light not slow down in the space dust and gas particles in space? In a piece of glass or water, does the light slow down when it enters at an angle of 90 degrees to the surface of the medium as it does when it enters at an angle? Why is light constant when something approaches or hits it at speed? For example if you travel at 86,000 miles per second why is the effective speed of light not 186,000-86,000 miles per second? Thanks