An unknown spectrum has a red line at 653 nm and a violet line at 450 nm. What angular separation between these two spectral lines is obtained with a diffraction grating that has 3,500 lines/cm

Asolid cylinder and a cylindrical shell have the same mass, same radius, and turn on frictionless, horizontal axles. the cylindrical shell has light-weight spokes connecting the shell to the axle. a rope is wrapped around each cylinder and tied to blocks of equal masses that are held the same height above the ground. both blocks are released simultaneously. the ropes do not slip. which block hits the ground first? or is it a tie?