Spheres Definition and 504 Threads

The Synchronized Position Hold Engage and Reorient Experimental Satellite (SPHERES) are a series of miniaturized satellites developed by MIT's Space Systems Laboratory for NASA and US Military, to be used as a low-risk, extensible test bed for the development of metrology, formation flight, rendezvous, docking and autonomy algorithms that are critical for future space missions that use distributed spacecraft architecture, such as Terrestrial Planet Finder and Orbital Express.Each SPHERES satellite is an 18-sided polyhedron, with a mass of about 4.1 kg and a diameter of about 21 cm. They can be used in the International Space Station as well as in ground-based laboratories, but not in the vacuum of space. The battery-powered, self-contained units can operate semi-autonomously, using CO2-based cold-gas thrusters for movement and a series of ultrasonic beacons for orientation. The satellites can communicate with each other and with a control station wirelessly. The built-in features of the satellites can be extended using an expansion port.From 2006, three SPHERES units are being used in the International Space Station for a variety of experiments. The SPHERES Guest Scientist Program allow scientists to conduct new science experiments using SPHERES units, and the Zero Robotics Program allow students to participate in annual competitions that involve developing software to control SPHERES units.The SPHERES program is expected to continue until 2017, and possibly further.The SPHERES project lead to a newer project called Astrobee.

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  1. W

    Electrostatic potential energy for concentric spheres

    Two concentric metal spheres have radii r_1 = 10 cm and r_2 = 10.5 cm. The inner sphere has a charge of Q = 5 nC spread uniformly on its surface, and the outer sphere has charge -Q on its surface. (a) calculate the total energy stored in the electric field inside the spheres Hint: You can treat...
  2. A

    Electromagnetism - Conducting Spheres and their potential

    Homework Statement Two hollow concentric conducting spheres hold charges Q[1] and Q[2] as shown in the attachment. Find the potential of each sphere, and the potential difference. Homework Equations Potential difference V = Phi[2] - Phi[1] The Attempt at a Solution I'm having...
  3. A

    Capacitance of a system of 3 concentric spheres

    1. 3 conducting spheres of radius a, b, c (a<b<c) are held at a potential of 0, V, 0 respectively. What is the capacitance of the system? 2. Q=CV (which I assume extends to Qi=CijVj for multiple conductors). 3. I've calculated the fields in the two interesting regions, calculated the charge on...
  4. O

    Describe Charge Distribution on Spheres After They Touch

    I am trying to correctly understand the following problem: Here is the setup: I have two conducting spherical shells. We will call them S-Left and S-Right. Both spherical shells are initially grounded, therefore, they have no net charge w.r.t. Earth. S-Right is hanging from a string. S-Left...
  5. A

    Solving Two Identical Conduction Spheres Problem

    Homework Statement Two identical conduction spheres are placed with their centers 0.30m apart. One is given a charge of 12 x 10 ^-9 C, the other a charge of -18 x 10 ^-9 C a) Find the electrostatic force exerted on one sphere by the other. b) The spheres are connected by a conducting wire...
  6. S

    Spheres, Plates, and Gauss' Law

    Homework Statement A sphere of radius 8.0 cm carries a uniform volume charge density rho = 500*10^-9 C/m^3. What is the electric field at r = 3.0 cm? a.36.0 N/C b.230 N/C c.140 N/C d.565 N/C e.450 N/C Homework Equations E = (k*Q*r)/(R^3), where...
  7. C

    Calculating the Speed of Charged Spheres Moving Away from Each Other

    Homework Statement Four 1.0 g spheres are released simultaneously and allowed to move away from each other. What is the speed of each sphere when they are very far apart? The Attempt at a Solution Here's what I got initial potential energy is equal to final kinetic energy. 0.9866...
  8. S

    Electric Force and Charged Spheres

    Homework Statement Consider the following configuration of fixed, uniformly charged spheres on an xy coordinate system: ·a blue sphere fixed at the origin with positive charge q. ·a red sphere fixed at the point (d1,0) with unknown charge q_red, ·a yellow sphere fixed at the point...
  9. resurgance2001

    Perfection of Atoms: Are They Truly Spherical?

    One of my students Chris wanted to ask this question: are atoms perfect spheres? I could have offered one of my own answers to this but I think he would prefer to hear what you guys have to say. The only thing I would say is that I like the question because of its apparent simplicity. I...
  10. T

    Need help with volumes of spheres with holes.

    Homework Statement if you guys have trouble reading that, it says, Suppose you make napkin rings by drilling holes with different diameters through two wooden balls (which also have different diameters). You discover that both napkin rings have the same height h, as shown in the figure...
  11. S

    Friction of spheres & cylinders

    Hi, I am doing a project involving spherical wheels. I need some help with regards to the role played by friction on motion of spheres and cylinders (normal car wheels) on roads. Will friction act forward or backwards ?? Which type of wheel would be more advantageous ? Would appreciate any...
  12. M

    Colliding Spheres Homework Problem - Find Answer in m/s

    Ive got this one homework problem that i am totally clueless on. Any help? "Two insulating spheres having radii 0.34 cm and 0.54 cm, masses 0.13kg and 0.58 kg, and charges -3x10^-6 C and 2x10^-6 C are released from rest when their centers are separated by 1.2m. How fast is the smaller sphere...
  13. B

    Exploring Probability Spheres in Fractional Dimension

    I have heard of such idea: A sphere of fractional dimension 0<s<1 is understood as a probability sphere with probability s to have an electron at a certain position for example the volume of the sphere S^{n-1} in \Re^n has volume Vol(S^{n-1})= (2\Pi^{n/2})/(\Gamma(n/2) and we can...
  14. M

    Unlock the Power of Conducting Spheres: A Comprehensive Guide

    two spheres are
  15. M

    Problem with polynomials and spheres

    Hi all, I've got this problem: Consider the points P such that the distance from P to A(-1,5,3) is twice the distance from P to B(6,2,-2). Show that the set of all such points is a sphere, and find its center and radius. I think the setup should be this: sqrt[(x+1)^2 + (y-5)^2 +...
  16. B

    Electric Potential of Two Spheres

    Problem: An insulated spherical conductor of radius r1 carries a charge Q. A second conducting sphere of radius r2 and initially uncharged is then connected to the first by a long conducting wire. After the connection, what can you say about the electric potential of each sphere? How much...
  17. F

    Two charged spheres repel (attached to strings)

    It's been awhile since I've had physics I, so this problem is giving me a headache. Q) Two very small conducting spheres, each of a mass 1.0 \times 10^{-4}\,\,(kg) , are suspended at a common point by very thin nonconducting threads of a length 0.2 \,\,(m) . A charge Q is placed on each...
  18. S

    How Does Electric Potential Apply to Spheres with External Charges?

    I have two problems that confuse me for similar reasons. The first one: Find the potential \varphi of an uncharged conducting sphere outside of which a point charge q is located at a distance l from the sphere's center. The second one: A system consists of two concentric conducting spheres...
  19. K

    Electrostatics charged spheres problem

    1)Two small equally charged spheres, each of mass m, are suspended from the same point by silk threads of length l.The distance between the spheres x<<l.Find the rate dq/dt with which the charge leaks off each sphere if their approach velocity varies as v=a/(x)^0.5, a is a constant...
  20. D

    Electric Force Question and Spheres

    Three identically charged spheres A, B, and C, each with a charge of +3.0 * 10-7 C, are located at the corners of a triangle whose sides are 30 cm long and all the angles are 60 deg. What is the net force acting on sphere A? I figured the X coordinates cancel each other out. For the Y...
  21. Amith2006

    What Is the Ratio of Thermal Conductivities and Rate of Cooling for Spheres?

    Sir, 1) Two spheres of different materials, one with double the radius and 1/4th wall thickness of the other are filled with ice. If the time taken for complete melting of ice in the large sphere is 25 minutes and that in smaller sphere is 16 minutes, what is the ratio of the thermal...
  22. J

    Solving a Physics Problem Involving Two Metal Spheres

    Hi, I have a physics problem I need to solve which I think is quite straight forward but would appreciate some input on whether I'm going down the right lines Tow metal spheres hanging from the roof one of 10g (ball1) and one of 100g (ball2) ball1 is falling from a height of 15cm...
  23. L

    Follow up on the 2 spheres capacitor problem. Help needed before tomorrow

    Follow up on the 2 spheres capacitor problem. Help needed before tomorrow! It was probably a bit hard to see what the old topic was about, so I started a new one. I'm still not quite sure on this problem, so I'd REALLY appreciate it if somebody could clear things up a little bit more. The...
  24. L

    Calculating Capacitance of Two Isolated Conducting Spheres

    The question is the following one: Two isolated conducting spheres of equal radius have charges +Q (#1)and -Q (#2) respectively. If they are separated by a large distance compared to their radius, what is the capacitance of this unusual capacitor? The first remark :wink: : C= \frac{Q}{V}...
  25. B

    Calculating Charge Distribution on Isolated Conducting Spheres

    The question i am stuck on and am unable to find anything in my notes about (although i can't find my notes from tuesday however we seem to have covered the topic on friday and maybe just not finished it off in time) is ... Two isolated spherical conductors one with radius R and one with...
  26. C

    How Many Electrons to Transfer for a 3.00e4 N Force Between Silver Spheres?

    Two small silver spheres, each with a mass of 12.0 g, are separated by 1.00 m. Calculate the fraction of the electrons in one sphere that must be transferred to the other to produce an attractive force of 3.00e4 N (about 3 tons) between the spheres. (The number of electrons per atom of silver is...
  27. F

    Two Identical Spheres and Displacement

    I am studying for my exam for physics and i came across 2 questions that i sort of need help with. 1. Two identical spheres, with charges of Qa=-2Q and Qb=1Q, attract one another with a force of 9.0 x 10^-4 N. A third identical uncharged sphere C touches B and now C is completely removed from...
  28. A

    Electrostatics - charges on spheres and work done in moving them

    hi, this is a great forum here and i was wondering if anyone could lend a helping hand , it would be great. im currently studying at univercity for electronics engineering and have been given some physics questions to work onover the holidays. I ahve spend quite some time on this question...
  29. A

    Finding electric field intensity of two spheres

    Any help on this question is appreciated. Two small spheres each of mass m are suspended by light strings of light L. A uniform electric field is applied in the x direction. If the spheres have equal and opposite charges of magnitude Q, determine the electric field intensity that enables the...
  30. M

    At what distance has spheres decreased Electric potential by 700V?

    Hello everyone, I managed to get Parts (a) and (b) of this problem but can't get the last for some reason. A metal sphere of radius 15cm has a net charge of 2.0E-8C. THe question is, at what distance from the sphere's surface has the electric potential decrased by 700V? Well i found the...
  31. P

    Calculating Angle Ratios in Electrostatic Systems

    the below figure make small angles theta1 and theta2 with the vertical. Figure 21-50 (a) If Q1 = Q, Q2 = 3Q, and m1 = m2 = m, determine the ratio theta1 / theta2. (b) If Q1 = Q, Q2 = 2Q, and m1 = m, and m2 = 4m, determine the ratio of theta 1 / theta 2. I don't get the forces that are...
  32. R

    Why Am I Getting Strange Results Measuring Sphere Densities?

    My question is regarding finding volume and densities of spheres. I'm getting strange results, so I thought I'd find out where my methods are incorrect. I am using a graduated cylinder to drop the spheres into with water inside. I measured the initial volume of the water before I dropped...
  33. K

    Will We Ever Utilize Dyson Spheres?

    In your opinion will we ever use Dyson Spheres? http://www.daviddarling.info/encyclopedia/D/Dysonsp.html In case you don't know what a Dyson spere is.
  34. C

    Measuring Spheres: How to Use the Formula (4/3 π r3)

    I have homework, the teacher gave us measuring spheres. He gave us the formula (4/3 π r3) But he didn't show us how to figure out the problem. I don't know how your suppose to figure it out.
  35. B

    What's the difference between a two sphere and a three sphere?

    Just a couple of questions: 1. If we imagine space to be curved over a sphere is it possible to travel in one direction and eventually end up where you started, assuming that the sphere it self is not expanding. 2. What's the difference between a two sphere and a three sphere? I find it...
  36. T

    Calculate the gravitational force between these spheres

    In introductory physics laboratories, a typical Cavendish balance for measuring the gravita- tional constant G uses lead spheres of masses 1.8 kg and 13.9 g whose centers are separated by 5.77 cm. Calculate the gravitational force between these spheres, treating each as a point mass...
  37. V

    Why Don't Surface Area & Volume Ratios of Spheres Match?

    Howcome the ratio of the surface area of spheres are not equal to the ratio of volume of spheres? For example if I had two spheres, with an aspect ratio of 1:4 when comparing surface areas, yet I have 1:8 between those same spheres when comparing volume. This doesn't make sense to me...
  38. S

    Calculating Charges of Two Small Nonconducting Spheres

    Two small nonconducting spheres have a total charge of 80 microC. When place 1.06 m apart, the force exerts on the other is 12 N and is repulsive. What is the charge of each. What if the force were attractive? Given: k, F = 12 N if repulsive but F = -12 N if attractive, Q1 + Q2 = 8 x 10^-5 C...
  39. M

    A question of charged spheres and voltages

    I have a question regarding charged spheres and voltage measurements. I've talked to my physics professor about it, and he wasn't quite sure of the answer (although to be fair, I asked briefly at the end of class.) Imagine that you had a spherical shell, charged to a high potential (for the...
  40. F

    Cell Membrane and Hollow Spheres

    there are 2 probs here. 1) The inner and outer surfaces of a cell membrane carry a negative and positive charge, respectively. Because of these charges, a potential difference of about 0.0680 V exists across the membrane. The thickness of the membrane is 7.95×10-9 m. What is the magnitude of...
  41. E

    Coulomb's Law of two copper spheres

    Here's a question from my textbook: Two copper spheres, each having a mass of .4 kg, are separated by 2 m. (a) How many electrons does each sphere contain? The atomic mass of copper is 63.5 g/mol, and its atomic number is 29. (b) How many electrons would have to be removed from one sphere...
  42. V

    What is the largest radius for 8 styrofoam spheres in a box?

    Heya, this is my first post, I hope it isn't too hard :smile: Alright, the problem goes like this. I put a sphere into a box to be shipped somewhere, it fits perfectly into the box and the sphere has a radius R. Now I have 8 styrofoam spheres that are placed on the corners of the box, find...
  43. M

    Electrostatic Forces on Charged Spheres: Calculations and Comparisons

    HELP HELP HELP! spheres! Consider a solid sphere of radius R containing a total charge Q which is uniformly distributed throughout the volume with a volume charge density rho. a) find the total force exerted by the electrostatic field on the charge in the 'northern hemisphere'. express your...
  44. J

    Vectory Geometry, problem involving spheres

    Hi ppl, ne1 know how to approach this one? Given P(1,4,-1), Q(1,2,-1) and R (3,2,-2), show that PQR is right angled and hence find the equation of the smallest sphere S which passes through P,Q and R. Okay, I got the right angle by showing PQ and QR to be perpendicular with the dot product...
  45. V

    Electric Potentials: concentric spheres

    Two concentric spheres of radii 1.65 cm and 19.0 cm, respectively, are given equal but opposite charges of 6.35e-08 C. How much energy is stored in the system (in J)? I know V = U/q where U would be the entire energy stored in the system beacuse it's not in motion. I know q's but I just...
  46. A

    How Does Gravitational Attraction Affect Potential Energy of Spheres in Space?

    Two spheres with radius of .10 m and a mass of 25 kg are floating in deep space. Their gravitational attraction keeps them in contact. If we go in and manually separate these spheres to a large distance, by how much will the potential energy involved in their interaction increase. Is there...
  47. N

    Two spheres collide and assume that the collision is perfectly elastic

    Two spheres collide and assume that the collision is perfectly elastic. Also --only linear momentum. I have the relationship: (va' - vb') dot N = -(va - vb) dot N Where N is the normal vector at the point of collision. va and vb are initial velocities of object A and B, respectively...
  48. A

    Electrostatics: suspended spheres

    Two small spheres of mass m are suspended from strings of length L that are connected at a common point. One sphere has charge Q, the other has 2Q. The strings make angles (theta1) and (theta2) with the vertical. (a) How are theta1 and theta2 related? (b) Assume theta1 and theta2 are...
  49. I

    Black hole might crunch the many planets into marble-sized spheres

    If the black hole has infinite capacity to store mass,why,in a case of the sucking up of the sun,why would their(crudely described)sunny-side up expel huge jet streams of flames and heat? Cant they absorb heat energy and UV since they have capacity to collect mass? If it is possible the Black...
  50. U

    Electric force between two spheres?

    Two identical small spheres possessing charges q1 and q2 are separated by distance r. Which charge would produce the greatest inecreas in the electric force between the tow spheres? 1. double charge q1 2. double r 3. double r and q1 4. double r, q1, and q2 I'm pretty sure it's #1
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