Rasheed runs a football 10 meters east, turns and runs the football 6 meters west. if his velocity during this run is found to be 3 meters/second, how long does this take rasheed to complete this run?

The two most prominent wavelengths in the light emitted by a hydrogen discharge lamp are 656(red) and 486 (blue). light from a hydrogen lamp illuminates a diffraction grating with 500 lines per mm, and the light is observed on a screen 1.50 behind the grating. what is the distance between the first-order red and blue fringes?