Question of the day

Q- Positive charge Q is distributed uniformly along the x-axis from x = 0 to x = a. A positive point charge q is located on the x-axis at x = a + r. 

(a) Calculate the x-component of the electric field produced by the charge distribution Q at points on the positive x-axis where x ...

Q- An iPod is left running inside a thin insulating case 2.5 mm thick with thermal conductivity of 0.02 W/K/m. The case is black and at 25 degrees Celsius and exchanges energy with it's surroundings, all of which are at 20 degrees Celsius, by radiation alone. What is the temperature inside the case?

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Q- A stick of length L is placed vertically by the wall. At its lower end sits a bug. The end B of the stick starts moving to the right with constant speed v, and at the same moment the bug starts crawling along the stick with speed u relative to the stick. What is the maximal height above the floor...

Q- Find the equivalent capacitance between points a and b in the combination of capacitors shown in Figure. C₁ = 2.0 µF and C₂ = 3.0 µF.

Solution:

Q- A solid cylinder, of radius c acted upon by no forces, moves parallel to its axis through a uniform cloud of fine dust, of volume density ρ, which is at rest. If the particles of dust which meet the cylinder adhere to it, and if m0 and u be the mass and the velocity at the beginning of the motion...

Q- Isotope 137 Cs of Cesium has a half life of 30 years. Suppose a distributor sells 5 grams of it in January 1, 2000. (a) Write an equation with giving the number of grams of the isotope left "t" years after January 1, 2000. (b) How many grams are present after 6 years?

Solution:

Q- A block with mass M attached to a horizontal spring with force constant k is moving with simple harmonic motion having amplitude A. At the instant when the block passes through its equilibrium position, a lump of putty with mass m is dropped vertically onto the block from a very small height and ...