A student leaving school walks 3.5 km north and walks 1.0 km south what is the students distance?

A150 w lamp emits light of wavelength 590 nm uniformly in all directions. what is the photon flux (photons per unit area per unit time) on a small screen at a distance 2.3 m from the lamp? assume the photons are uniformly distributed over the surface of a sphere of radius 2.3 m.

Which of the following is a measure of the amount of light a star directly emits?               a.  luminosity    b.  intensity    c.  wavelength    d.  brightness

Which of the following are forms of phase changes a. freezing b. condensation c. heating d. exchanging