A person with a surface temperature of 35 C emits about 1.36 1022 photons per second

Question:

A person with a surface temperature of 35 °C emits about 1.36 × 1022 photons per second into an environment at 20 °C. Suppose the person has a mass of 70.0 kg and stands on a frictionless surface. Find the recoil speed of the person after 1.00 h assuming all the photons are emitted in the same direction with a wavelength of 16 (m?