Diffraction from compact discA laser beam of wavelength 632 nm shines at normal incidence on the reflective side of a compact disc.

a) The tracks of tiny pits in which information is coded onto the CD are 1.60μm apart. For whatangles of reflection (measured from the normal) will the intensity of light be maximum?
b) On a DVD, the tracks are only 0.74μm apart. Repeat the calculation for that DVD.

Arunner is jogging at a steady 3.6 km/hr. when the runner is 2.9 km from the finish line, a bird begins flying from the runner to the finish line at 14.4 km/hr (4 times as fast as the runner). when the bird reaches the finish line, it turns around and flies back to the runner. even though the bird is a dodo, we will assume that it occupies only one point in space, i.e., a zero-length bird. how far does the bird travel? (b) after this first encounter, the bird then turns around and flies from the runner back to the finish line, turns around again and flies back to the runner. the bird repeats the back and forth trips until the runner reaches the finish line. how far does the bird travel from the beginning? (i.e. include the distance traveled to the first encounter)

This energy transformation diagram represents the energy of a skateboarder moving along a half-pipe. as she skates toward the top of the half-pipe, her original kinetic energy is converted to potential energy and friction. how much of the energy is potential?

If the area of a square has increased by a factor of 16, by how much has each side increased?