A solid cylindrical pulley has a radius of 8 cm and a mass of 220 grams. A string of negligible mass is wrapped around the circumference of the pulley wheel and a 50-gram mass is attached to the free end of the string and allowed to hang freely. The system is released from rest and the box descends 1.4 meters.
(a) What is the linear speed of the box after this descent?
(b) What is the tension In the vertical length of the string at that moment?

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.

What would be the result of an alpha particle coming into a magnetic field? a) the alpha particle will stop moving. b) the alpha particle will reverse its direction. c) the alpha particle will be deflected in a curve path. d) the alpha particle will continue to travel in a straight line.

Estimate of the number of stars in our galaxy