Ajani is trying to experimentally measure Planck's constant h. He does this by shining different wavelengths of monochro- matic (i. e., single-wavelength) EM radiation on a metal plate with unknown work function W, and then measuring the stop- ping voltage required to bring the ejected electrons to a halt. When he uses λ1= 400 nm, he finds that a stopping voltage of V1 = 0.7 V is required. When he uses λ2 = 500 nm, he finds that a stopping voltage of V2= 0.2 V is required. Based on these two data points, what is Ajani's measurement of Planck's constant?

Your starship, the aimless wanderer, lands on the mysterious planet mongo. as chief scientist-engineer, you make the following measurements: a 2.50-kg stone thrown upward from the ground at 14.0 m/s returns to the ground in 5.70 s ; the circumference of mongo at the equator is 2.20×10^5 km ; and there is no appreciable atmosphere on mongo. (a) the starship commander, captain confusion, asks for the following information: what is the mass of mongo? (b) if the aimless wanderer goes into a circular orbit 2.20×10^4 km above the surface of mongo, how many hours will it take the ship to complete one orbit? (c) an unmanned spacecraft is in a circular orbit around the moon, observing the lunar surface from an altitude of 44.0 km . to the dismay of scientists on earth, an electrical fault causes an on-board thruster to fire, decreasing the speed of the spacecraft by 23.0 m/s . if nothing is done to correct its orbit, with what speed (in km/h) will the spacecraft crash into the lunar surface?