# Search results

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

well i didnt put brackets in right place. should be (20.97l/m /60) * 10^-3 = m^3) =3.495*10^-4 still doesnt solve prob though. any other help?? please help!??
3. ### 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...
4. ### Ice displacing water question, -need help really bad

(1.1 x 6 x 6) x 917/1025 m = 35.428cm (the amount of water displaced). So, the ice sticks out of the water 1100-35.428 = 1064.572cm = 1.064m still wrong though ????
5. ### 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...
6. ### 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...
7. ### Hydralic lift

sorry for the redirect, but i am alot further along on this problem and posted different question (from the same problem) https://www.physicsforums.com/showthread.php?p=1572416#post1572416
8. ### 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...
9. ### 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...
10. ### 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...
11. ### Please explain equipotential surfaces/ contour maps

Ok thanks, that helps, but now i guess im having prob with the actual word. "EQUI" .... --what exactlly is equal in the contour map? i am assuming equi word root means "equal"
12. ### 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...
13. ### 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...
14. ### Circuit with 2 batteries is confusing me

1.421V is wrong answer though, so can u please tell me what im doing wrong? thanks
15. ### Circuit with 2 batteries is confusing me

because picture says current is going cw, so 1st batt is -4V and 2nd batt is 6V = 2V so 2V enters Req. Req = 2ohms and total current in the circuit is .286A so V=IR = .286 X 2ohm = .579V 2V - .579V = 1.421V
16. ### 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...
17. ### Ohms law problem

ok i needed to relearn circuit breakdown and then build it back up. thanks
18. ### Ohms law problem

why do i need to know voltage drop across r4? also does it matter which dorection the current is going?
19. ### 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...
20. ### 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...
21. ### 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
22. ### 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...
23. ### 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...
24. ### 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...
25. ### 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...
26. ### 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...
27. ### 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
28. ### Spring constant with point charges

Dont I need the spring constant to get the PE stored in the spring though? PE (in spring) = ( 1/2 k (delta s)^2)
29. ### 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...
30. ### Coulombs law not working

UPDATE: i was saying that 11cm = .011m that was prob. One other question though. Why does the opposing charge have to be negative??