# carrotstien

Members

19

## Community Reputation

10 Neutral

• Rank
Quark
• Birthday 03/29/1988

## Profile Information

• Location
Staten Island, NY
• Interests
sports, figuring out stuff, eating
• College Major/Degree
Cooper Union, Interdisciplinary Engineering
• Favorite Area of Science
Physics
• Occupation
n/a :-p too lazy
1. ## What causes the perpindicular (to the r vector) velocity of a planet to change?

thanks Mr Skeptic. I understood that, but for some reason after you said it it all began to make sense. The speed gets changed by the tangential force, while the perpendicular force later takes this increases speed and changes its direction.
2. ## What causes the perpindicular (to the r vector) velocity of a planet to change?

I understand that from the laws of conservation of momentum and energy the velocity must increase. That, however, doesn't answer my question. My question is of a lower level than that. Why is the speed of an oject moving in a circular orbit always constant, or why does the speed of a charged particle moving in a magnetic field always constant (not counting radiation losses), because the force is always perpindicular to velocity, so that it can only change the direction but not the magnitude. In the elliptical case, the force is always perpindicular the perpindicular componant of the veloci
3. ## What causes the perpindicular (to the r vector) velocity of a planet to change?

Take earth orbiting the sun. The path that earth takes is an ellipse where the sun is at one of the foci. At one time, earth is the closest to the sun and moving the fastest, while at another time, earth is farther from the sun, and travels slower. My question is thus: Lets say you take the velocity at any moment and you seperate it into two components, one parallel to the line connecting earth and the sun (the r vector), and on perpindicular to the r vector. Since the force between earth and the sun is always in the direction parallel to the r vector, and always perpindicular to the perpind
4. ## How do you determine the distribution of frictional forces among the tires of a car?

I understand that that the outside are accelerating faster than the inside. But, why would anyone of these be invalid (when the mu's are high enough to sustain them) ~sum of forces from outside tires = mv^2/R and the other tires don't do anything. where mass of car is M and radius of center of mass' motion is R ~vice versa ~each tire applies the same force as long as the sum of all the forces is mv^2/R and torques add to 0 I am not sure about the last one, but the first two are perfectly feasible since they are describing a 2 wheeled motorcycle with a center of mass off the line
5. ## How do you determine the distribution of frictional forces among the tires of a car?

When the car is moving in a circle at a constant velocity, how would you figure out the forces that come from each wheel (in the case that the max friction of each tire is much greater than anything encountered). For a motorcycle i figured it out easily - it comes out to simple solving two equations: sum of torques around center of mass = 0 sum of forces on body = centripetal acceleration = mv^2/R = mRw^2 This can even be solved for a two wheeled car, where instead of the other set of wheels, you have frictionless pegs. Is there a way to solve it, or does it work in a way tha
6. ## Linear and Angular Accel

There is a thin ring of mass M radius R. At each direction, north, south, east, and west, you have a rocket that pushes with a constant F newtons. Each rocket push vector is Nx,Ny, Ex,Ey, Sx,Sy, and Wx,Wy. The ring's center of mass is moving at V so that Vx and Vy are the components of velocity in the x and y direction respectively. The ring is also spinning with an angular velocity of Z radians per second clockwise. The rockets are much lighter than the ring so that they don't really affect any calculation due to their relatively small mass. What are the linear and angular accelerations
7. ## Domino Challenge

nice, i would have loved to try that, but i don't have any dominoes. I did something like that with heavy backgammon pieces, but there aren't that many of them, and they obviously weren't standing on their smaller sides
8. ## Where Does Space End? It Must End Somewhere!

I was under the impression that 'universe' meant everything everywhere, which is made up of, matter floating around in space. Space, is just a container for matter. So the question is how large is this container. (atleast i think thats the question), because if the question is about the size of the volume whose boundaries are defined by actual energy/matter being there, then the question isn't whether space ends, but whether there is a limited amount of matter in the universe spread over a finite volume at any specific moment (so that volume is expanding.) Otherwise, if space is only wher
9. ## Where Does Space End? It Must End Somewhere!

When you say that the universe is expanding, do you mean the volume taken up by mass, or the actual region that mass could theoretically take up space in. If you are saying that space itself is expanding, how fast is it expanding. If the size of space depends on mass, then i guess the rate of expansion of space can't be the speed of light. So what would happen if you travel faster than the rate of expansion till this ever expanding edge? I imagine a cup of honey. You pour all of it onto a table. At first, you get a thick bulging circle of honey. As time progresses the radius of this circ
10. ## Where Does Space End? It Must End Somewhere!

If after the explosion all the mass makes a circular distribution as you would expect from an explosion, then the gravity starting from the boundary of the distribution acts as though all the mass is at the center of the distrubtion. So, as the radius of distribution gets larger, each piece of matter gets further and further away from the center. If at any time all the matter forms a circular distribution, then the center of the circle along the surface of the sphere is at two points at all times. So, in a sense, a point at one pole, is a circle of a radius equal to half the circumfe
11. ## Effects of offcenter forces...

i attached a Word document, maybe its easier to read with the sub and super scripts and *'s math.doc
12. ## Where Does Space End? It Must End Somewhere!

This is by far the most philosophical question of physics. Possibilities: 1: The shape/size/geometry of the universe is something that we cannot actually mentally grasp so that we cannot say anything absolutely true about it. 2: Space is infinite in a way that you can, if you lived forever and space didn't blink out of existence for any unknown reason, travel in a perfectly straight line (somehow garanteeing that is perfect) and go on for an infinite amount of time without ever seeing anything perfectly repeat or every reaching a limit/boundary. 3: Space is something that is ben
13. ## A doubt in the Law of conservation of energy

Kinetic energy is something which is actually relative. If I am moving along a straight road at 1m/s and i have a mass of 60kg, what is my kinetic energy? Could you say that it is 60kg * (1m/s)^2, what about that velocity, to some viewers I could be seen moving at .5c in one way or .6c the other way or not moving at all. About the ball: You are doing work to the ball by slowing it down, this work is equal to F dot X which ends up to be -FX. So you are doing negative work. If you count the kinetic energy of the ball before hand add (-FX) you will get 0 which explains why you see the ball sto
14. ## Effects of offcenter forces...

If you have a rod, or more simply 2 very small masses connected by a massless rod of length L (each mass being equal; M kgs.) You then connect a massless rocket thruster an x distance to the right of the center of the rod so that the thrust is always F newtons perpendicular to the rod. How would the system behave? O, and before people start saying how massless things don't work, then say that the mass of the rod is .0000000001 * M and the material behind ejected out of an equally light rocket is lighter a million times lighter than that, but is going at a very very large velocity close to the
15. ## Can anyone else solve this? Inclined plane super problem

attachments...are attached, lol
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