What is the approximate wavelength of a light whose second-order dark band forms a diffraction angle of 15.0° when it passes through a diffraction grating that has 250.0 lines per mm?

Which is the best for showing percentages of different types of cars sold(gas hybrid , electric , other ) in the united states ?

1. jay fills a wagon with sand (about 20 kg) and pulls it with a rope 30 m along the beach. he holds the rope 25° above the horizontal. the rope exerts a 20-n tension force on the wagon. how much work does the rope do on the wagon?

The two stars in a certain binary star system move in circular orbits. the first star, alpha, has an orbital speed of 36 km/s. the second star, beta, has an orbital speed of 12 km/s. the orbital period is 137 d. a) what is the mass of the star alpha? b) what is the mass of the star beta?