# Yahoo Web Search

1. ### Derive a relation between the potential V and the magnitude of the field E at a radial distance, r , from the a?

Answer ... V = - r E • ln [ r / a ] ... Consider the rod as a very long uniformly ...z-axis and that the field point lies on the xy-plane at a perpendicular distance r from the cylinder axis … by taking an imaginary cylindrical Gaussian surface...

1 Answers · Science & Mathematics · 10/08/2012

2. ### How do u calculate r -value (Measure of thermal resistence)?

R -value is measured in meter²·°C/Watt (in the...·°F·h/Btu). Materials may be rated in R /inch, R /meter, etc. To calculate the R -value of a wall, you calculate...

2 Answers · Science & Mathematics · 27/02/2010

3. ### Consider the circuit shown in the figure below. ( R = 27.0 Ω.)?

R and 5 Ω are in series => their equivalent resistance = 27 + 5... 32 Ω, 5 Ω and 10 Ω are in parallel. If R ' is their equivalent resistance, 1/ R ' = 1/10 + 1/5 + 1/32...

2 Answers · Science & Mathematics · 28/07/2010

4. ### For Torque, when do you use (F x r ) and (Fd)?

r x F is the definition of torque, where r and F are vectors and "x" means the vector cross...

1 Answers · Science & Mathematics · 16/12/2009

5. ### why centripetal acceleration a=v²/ r ?

...with speed v traveling in the +y direction and it is at a location of x= r , y=0. It is circling around the origin as you would likely guess...

3 Answers · Science & Mathematics · 23/11/2010

6. ### What is r -hat cross phi-hat in spherical coordinates?

r -hat cross phi-hat = theta-hat r -hat is the unit vector in a direction in which only r changes and theta and phi...and theta-hat is the unit vector in a direction in which only theta changes and r and phi remain constant.

1 Answers · Science & Mathematics · 07/01/2012

7. ### Why does the electric field around a dipole fall off as r ^3?

For the 1/ r ^2 law, it's because the flux of the electric field through a closed surface is constant. As r increases, the surface area of the sphere of radius r increases proportional to r ^2 (specifically 4r^2). Therefore the flux...

3 Answers · Science & Mathematics · 03/04/2013

8. ### PHYSICS: Given the equation F= mv2 / R , What relationship exists between...?

F = (m x v^2) / R a. If F increases, what in the right hand equation must R ...decrease. Do you see that there is an "inverse" relationship between R and F if (m x v^2) remains unchanged? b. F and...

2 Answers · Science & Mathematics · 14/09/2009

9. ### The Cartesian coordinates of a point in the xy-plane are (x, y) = (-3.61, -2.85) m. Find the polar coordinates?

x^2 + y^2 = r ^2 so r = sqrt(3.61^2 + 2.85^2). Theta = arctan (y/x) but since both x and...

1 Answers · Science & Mathematics · 12/01/2014

10. ### PHYSICS HELP: effect of R on weight?

R is your distance from the centre of mass of the Earth...or move to the equator ) you increase the distance from the centre ; you increase R , and reduce the force of attraction between you and the Earth... increasing...

2 Answers · Science & Mathematics · 12/09/2012