In Chapter 23 (Example 23.3), we discussed the use of a solar sail to propel a spacecraft. Such a sail would either absorb or reflect light from the Sun, using the resulting impulse to produce a force on the spacecraft. Consider a red laser that emits photons with a wavelength of 620 nm. 

(a) If this laser has a power of 30 W, how many photons does it emit in 1.0 s? 

(b) If the light emitted by the laser is absorbed by a black sail, what is the force on the sail? 

(c) If the light from this laser is reflected from a mirror, what is the force on the mirror?