Questions tagged [homework-and-exercises]

Applies to questions of primarily educational value - not only questions that arise from actual homework assignments, but any question where it is preferable to guide the asker to the answer rather than giving it away outright. Please READ THE GUIDANCE IN META before asking homework-like questions.

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How can I prove poisons equation from direct substitution

I’ve got this question where I should take the laplacian of electric potentials main formula, then it should hold the poisson’s equation. I’ve somehow gotten close to doing this but I just can’t get ...
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Magnetism question from REE (Roorkee Entrance Examination) 1991 [on hold]

A short magnet of magnetic moment 6 A.m2 is lying in a horizontal plane with its North Pole pointing 60 degrees east of north.Find the net horizontal magnetic field at a point on the axis of the ...
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Frame of Reference in Kinematics

If we have two frames of reference, say S1 and S2, and the acceleration of a particle as seen from both the frames has equal magnitude, say 4 m/s^2, then shouldn't the frames have no relative ...
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Line charge inside a conducting sphere?

I could not find any example like below. How can we solve this question? I tried to solve like sum of the point charges along the z axes but I am not sure if I am wrong or right. I think the shape of ...
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What is the best angle to throw a rock across a distance? [on hold]

If i were to throw a piece of rock, across a river of x metres wide, what would be the best angle of elevation i should throw the rock with, so that the rock can land x metres away with minimum force ...
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How do i calculate the speed of the ball? [on hold]

A spring pushes a 15 grams ball with 10 m/s in a bent pipe. What is the formula to calculate the speed of the ball in point A and point B. The pipe is horizontal so there is no g-force and the pipe ...
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In the circuit the switch was in position 1 for a long time and at t=0, it is thrown to position 3. Find current as function of time t after switching

I started solving the problem by finding the steady state current. Then as the switch was shifted to position 3 the current in the inductor would decay. But my teacher told me that the current ...
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Lagrangian mechanics a cylinder on a cylinder barrel

This is a typical problem to be solved using the Lagrangian mechanics, but I have a problem in understanding the rotational energy. The task is to formulate the Lagrangian equation for the system of ...
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Finding the average speed plus a break [on hold]

I have the following equation when the driver drove 2.5h at 120 km/h and then stopped for 30 minutes. Then he drove for 20 minutes at 25 m/s. The result of the equation is to determine the average ...
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Direction of acceleration vector at the apex of a curve

(Test Your Understanding of Section 3.2) The question wants me to choose the correct acceleration vector, from the given 9 options where 9th option is zero acceleration. Ok, first I thought option ...
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Electric potential of a charged spherical conductor using laplace equation

Reviewing a course of electromagnetism I encountered the problem of a spherical conductor with a charge of $Q$ in a uniform electric field. The problem of a conductor in a uniform electric field (a ...
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Path integral XY model

I am given the Hamiltonian for the XY model of spins $$H[\theta] = \frac{K}{2} \int |\nabla \theta|^2dxdy,$$ where $K = J/k_B T$ with $J$ the interaction energy between neighbouring spins. I ...
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