A totally reflecting disk has radius 9.00 micrometers, thickness 2.00 micrometers, and average density 700 kg/m^3. A laser has an average power output Pav spread uniformly over a cylindrical beam of radius 2.00 mm. When the laser beam shines upward on the disk in a direction perpendicular to its flat surface, the radiation pressure produces a force equal to the weight of the disk. What value of Pav is required?
(The answer is 25.9 W, but I'd like to know how to get it)

What average laser power is required if the radius of the disk is doubled?

what is the question?

answer: the exterior temperature of commercial jet planes as they leave the stratosphere and return to the ground increases steadily.

explanation:

the lower most layer of atmosphere is troposphere which extends from 0 to 12 km above the surface of the earth. the temperature initially decreases as distance is increased from the earth's surface. commercial jets fly in lower part of the stratosphere. the stratosphere extends upto 50 km. the temperature in stratosphere starts rising again due to presence of ozone which traps the uv rays.

thus, when the planes leave the stratosphere and return to the ground, the exterior temperature increases steadily.

laticia draws the diagram below to show earth’s magnetic field.

answer

the arrows to the right of earth should point up.