Recent content by sokratesla

# If there is no motion in a direction, then the sum of the forces in that direction is zero. # Here there is no motion in the horizontal direction. The other for in the horizontal direction is the friction. From this info you can find the friction. # The force which makes the box go up is the...

# Hi, # To solve this question, you should learn what kind of a magnetic field a current flowing in an infinitely long wire creates. The field due to two wires is just the superposition of itself. # Draw crossing lines from top view. For both lines indicate whether the field is into the paper or...

# Oh, yes. I did not see x there. Then, I think your reasoning seems plausible. You should write -k in units of N/cm there.

# It would enough for me if I were your teacher.

# Hi # for (i) Yes you are right. The thing will not start to rotate until the moment due to force exceeds the moment of weight. # (ii) For calculating the moment one looks at the perpendicular distance between the force vector and the pivot point and they are the same for figure I and II. but...

# Hi # I think there may be a mistake in the question. The dimensionality of the force is N not N/cm.

I think your answer is correct. Have confidence in your reasoning. :-) Their periods are exact means that you found an interesting result! First question is related to simple harmonic oscillation: \frac{d^2r}{dt^2}=-\frac{g_0}{R_E}r where \omega=\sqrt{\frac{g_0}{R_E}}. And second problem is...

# I would first look at the definitaion of a a(t) = \frac{dv(t)}{dt} # Integrate both sides \int^{t}_{t_0} a(t) dt = v(t) - v(0) # This is the relation between v and a. but it is not in the form of you want, i.e. v=f(a,t). It is an integral equation. # So, there should be an assumption...

# Radiation needs "sinusodially varying electric field" For example, if a charged particle makes an oscillation in space, its electric field makes and an oscillation with a delay in time, according to the distance of the field point to the source. # And light is an EM radiation (which is...

# OK, then. As you said the derivative of the function is 0 at x=0, and x=-2 and they are in the interval [-2,1]. By further calculating the second derivative or just plotting, or sketching the function, you can see whether these points are minima or maxima (or saddle points etc). And f(0) and...

# Thanks. But I know the names of V and A. :-) We need the names of these formulas which involve the variable \lambda.

# You found the answer by yourself. The question is whether there are any extremum points in the given interval (from 1 to 2) and the points you found are not in the given interval.

# The matricies are just some mathematical tools (a bunch of numbers) and have different meanings in different contexts. So, the meaning of transposing a matrix is context dependent too. # For example, we use matricies in coordinate transformations v'=Av where v' = \begin{pmatrix} x' \\...

# Hi # My instructor of EM course wrote two formulas on the blackboard and asked whether they are correct and what their names are. (He does not know the answers too) # These formulas give V and \vec{A}, given \vec{E} and \vec{B} V(\vec{r},t) = - \vec{r} \cdot \int_{0}^{1} d\lambda...

# It's and electrodynamics exam. In general, the exams are openbook or instructors give some important formulas. But they are all physics books and formulas. # And, I think, it's a shame for last year physics students, like me, not able to solve basic integrals.:shy: # Thanks for your help.