A construction crane lowers a beam into place at constant speed. Consider the work Wg done by gravity on the beam and the work WT done by the tension in the cable on the beam. Which is true?

A) Wi is positive and Wr is positive.
B) We is positive and W'r is negative.
C) Wg is negative and W'r is negative.
D) Wi and W'r are both zero.
E) None of the above

Suppose that an electromagnetic wave which is linearly polarized along the x−axis is propagating in vacuum along the z−axis. the wave is incident on a conductor which is placed at z > 0 region of the space. the conductor has conductivity σ, magnetic permeability µ and electric permittivity ε. (a) find the characteristic time for the free charge density which dissipates at the conductor. (b) write the maxwell equations and derive the wave equation for a plane wave propagating in a conductor. (c) find the attenuation distance at which the incident amplitude reduces to e ^−1 of its initial value. (d) find the electric and magnetic fields inside the conductor. 8 (e) find the power loss per area of the incident electromagnetic wave at the surface of conductor.

Aboy with a mass 25 kg climbs into a small tree. he sits on a branch that is 2.o m above to the ground.what is his gravitational potential energy above the ground?

The three classes of rocks are sedimentary, metamorphic, and igneous. how are rocks classified into one of these three groups?