21. The mass, radius, and gravitational field intensity of the moon are [tex]7.2 \times 10^{23} \, \text{kg}[/tex], [tex]1.7 \times 10^{6} \, \text{m}[/tex], and [tex]1.66 \, \text{N/kg}[/tex] respectively.
Find the weight of a man with an 80 kg mass on the moon.