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  1. M

    Distance in 3D

    Homework Statement If distance |AB| = root 83, and i also know that |PA| is twice |PB|, then how do you find? |PA| or |PB| ? The whole question states: 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...
  2. M

    What am i doing wrong (water thru a tube question)

    Homework Statement A tube of radius 6.000 cm is connected to tube of radius 1.000 cm as shown above. (see attachment).. Water is forced through the tube at a rate of 20.97 liters/min. The pressure in the 6 cm tube is 1.015×105 Pa. The density of water is 1000 kg/m3. Assume that the water...
  3. M

    Ice displacing water question, -need help really bad

    ice displacing water question, --need help really bad Homework Statement A rectangular block of ice 6 m on each side and 1.1 m thick floats in seawater. The density of the seawater is 1025 kg/m3. The density of ice is 917 kg/m3. How high does the top of the ice block float above the water...
  4. M

    Yes, this is a dumb question. sorry

    Homework Statement how are litres related to meters???? (with respect to flow rates. so for eg, if something goes 20litres per minute, then how do you convert that to the fluids velocity?? (so i think im having probs cuz i cant seem to get the difference between a litre and a meter...
  5. M

    Hydralic lift

    Homework Statement A hydraulic lift has two connected pistons with cross-sectional areas 5 cm2 and 550 cm2. It is filled with oil of density 520 kg/m3. a) What mass must be placed on the small piston to support a car of mass 1500 kg at equal fluid levels? this was no prob. =13.61...
  6. M

    Hydralic lift

    Homework Statement A hydraulic lift has two connected pistons with cross-sectional areas 5 cm^2 and 550 cm^2. It is filled with oil of density 520 kg/m3. a) What mass must be placed on the small piston to support a car of mass 1500 kg at equal fluid levels? Homework Equations...
  7. M

    Bernoulli problems

    Homework Statement A long horizontal hose of diameter 3.8 cm is connected to a faucet. At the other end, there is a nozzle of diameter 1.8 cm. Water squirts from the nozzle at velocity 38 m/sec. Assume that the water has no viscosity or other form of energy dissipation. a) What is the...
  8. M

    PD between 2 points

    Homework Statement a current of 2A is flowing from a to b. what is the potential difference between the points? ______a______3ohm_____-20V+_____1ohm_______+6V-________b_____ hopefully my diagram makes sense. Homework Equations this is a really simple question and i cant answer...
  9. M

    Please explain equipotential surfaces/ contour maps

    Homework Statement Can someone please define contour map for equipotential surfaces in really simple terms. I understand that the potential diff is from the neg side I dont understand what it means when the lines are closer together? I thought the lines are just divisions of the voltage...
  10. M

    Circuit with 2 batteries is confusing me

    Homework Statement The circuit in the figure is composed of two batteries (E1 = 6 V and E2 = 4 V) and three resistors (R1 = 4 , R2 = 4 , R3 = 5 ) as shown. (a) What is the current I3 flowing through the batteries? I3 = .286A (no problem here) (b) What is the voltage Vb - Va...
  11. M

    Ohms law problem

    Homework Statement Calculate the equivalent resistance of the network shown in the diagram. The resistances are: R1 = 12 ohm, R2 = 5 ohm, R3 = 15 ohm, and R4 = 15 ohm. no prob here Req = [(1/12)+(1/5)+(1/15)]^-1 + 15 = 17.86ohm When a battery with E = 6 V and zero internal...
  12. M

    Can equations have more than one side to them?

    Homework Statement Yes i know its an odd question, but when someone (trying to sound scientific) says "but remember, equations always have at least 2 sides to them" ..well technically thats not really true is it??? I Are there equations with more than 2 sides to them?? (This is in homework...
  13. M

    How can area be a vector? (flux equation)

    Homework Statement How can area be a vector? ( flux = E-vector dot product A-vector ) ? Homework Equations The Attempt at a Solution
  14. M

    Cant understand Gaussian surface

    Homework Statement Can someone please explain what use gaussian surfaces have, in really simple terms? I don't really understnd the point of wrapping an imaginary surface around a charge, when we can just do the calcs without the imaginary surface. Also if there are preset gaussian surfaces...
  15. M

    Gauss' Law problem

    Homework Statement An insulator in the shape of a spherical shell is shown in cross-section above. (see attached .gif) The insulator is defined by an inner radius a = 4 cm and an outer radius b = 6 cm and carries a total charge of Q = + 9 mC (1 mC = 10-6 C). (You may assume that the charge...
  16. M

    Three charges in a line (need help fast -please? (thanks))

    three charges in a line (need help fast --please? (thanks)) Homework Statement Two charges Qc and -Qc(Qc = 6 µC) are fixed on the x-axis at x = -8 cm andx = 8 cm, respectively. A third charge Qb = 2 µC is fixed at the origin. (attached .gif file shows the diagram) A particle with charge q...
  17. M

    Square array (electric field question)

    Homework Statement Four charges q1 = q3 = -q and q2 = q4 = +q, where q = 6 µC, are fixed at the corners of a square with sides a = 1.3 m. (see attached .gif) Calculate the x- and y-components of the net electric field at the midpoint M of the bottom side of the square. Homework...
  18. M

    Cant get y-component of point charges on test charge

    Homework Statement Six point charges, four positive (+q) and two negative (-q), are fixed at thepositions shown (i attached a .gif file --pls tell me if this isnt visable) in the x-y plane; q = 2.1 × 10-6C and a = 0.93 m. A test charge Q = 0.6 × 10-6C is at the origin. (a) Find the x- and...
  19. M

    What is a test charge?

    Homework Statement When a problem says: "a test charge is placed at the origin" are we to assume its a positive charge?? (it doesn't say in this prob) If the question says that the test charge is Q = 0.6nC --then i should assume pos right? Homework Equations The Attempt at a Solution
  20. M

    Spring constant with point charges

    Homework Statement Two charges Qa = 3 µC and Qb = -3 µC are placed on the x-axis with a separation of a = 21 cm. (a) Find the net electric field at point P, a distance d = 13 cm to the left of charge Qa. This is no prob = -1364069.13N (b) Find the force on Qb due to Qa . No prob...
  21. M

    Coulombs law not working

    Homework Statement A rigid, insulating fiber runs along a portion of the y-axis; the fiber isnot free to move. Gravity acts downward (g = 9.81 m/s2).A charge Qa = -7 µC is fixed to the fiber at the origin. A bead with a hole drilled through its center is slipped over the fiber andis free to...
  22. M

    Pendulum swing -basic trig problems

    pendulum swing --basic trig problems Homework Statement lets say you have a pendulum swinging. the length of string is 1m it swings to the right so that the angle is 45deg. i want to find difference in height from when it is at rest to its new position at 45deg. How do i do this...
  23. M

    Dropping coal on a platfrom (energy cons)

    Homework Statement A railroad hopper car weighs 20000 kg when empty and contains 10000 kg of coal. As it coasts along the track at 9 m/s the hopper opens and steadily releases all the coal onto a platform below the rails over a period of 5 s. Homework Equations d) If the coal fell 5 m...
  24. M

    Stretched spring -find coeff of friction

    stretched spring --find coeff of friction Homework Statement A relaxed spring with spring constant k = 70 N/m is stretched a distance di = 66 cm and held there. A block of mass M = 10 kg is attached to the spring. The spring is then released from rest and contracts, dragging the block across...
  25. M

    Missing sumthing really dumb. Please help?

    Homework Statement A block of mass M = 3 kg is released from rest and slides down an incline that makes an angle q = 32° with the horizontal. The coefficient of kinetic friction between the block and the incline is µk = 0.15. What is the acceleration of the block down the inclined plane...
  26. M

    Conserved momentum (car accident)

    Homework Statement A blue car with a mass of 2000 kg and a yellow truck with mass 9000 kg enter an intersection. The truck comes from the south at vtruck = 7 m/s, and the car comes from the west. When the two collide they stick together and slide at an angle of q = 43° north of east. What...
  27. M

    2 carts, a string, what is the work done?

    Homework Statement A cart of mass M1 = 6 kg is attached to a block of mass M2 = 3 kg by a string that passes over a frictionless pulley. The system is initially at rest and the table is frictionless. After the block has fallen a distance h = 1 m, What is the work Ws done on the cart by the...
  28. M

    Energy conservation (2 carts and a spring)

    Homework Statement A massless spring of spring constant 20 N/m is placed between two carts. Cart 1 has a mass M1 = 5 kg and Cart 2 has a mass M2 = 2 kg. The carts are pushed toward one another until the spring is compressed a distance 1.5 m. The carts are then released and the spring pushes...
  29. M

    2 blocks, on ontop of the other

    Homework Statement block A is ontop of block B. block A more mass than B Which force is greater magnitude, Force of gravity (mg (weight) on block B, or force of block A on B? Wouldnt answer have to be Faonb because both blocks are subject to gravity? Homework Equations The...
  30. M

    Hand pushes block

    Homework Statement Not an actual HW problem, but related to alot of probs i'm doing. Lets say a hand pushes a block across a surface (with friction). You take pic of 2 timepoints 1) when hand pushes block 2) After hand has let go and block is slowing due to friction Now when I draw the...
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