Answer to Question #117742 in Mechanics | Relativity for ran li

Question

A cheerleader standing at the top of a human pyramid has 1801 J of gravitational potential energy. If the
cheerleader is 4.50 m above the surface of the earth, her mass must be
a) 20.4 kg
b) 31.7 kg
c) 40.8 kg
d) 95.4 kg

Answer 1

The gravitational potential energy of cheerleader

$PE=mgh$

Hence, the mass of cheerleader

$m=\frac{PE}{gh}=\frac{1801\:\rm J}{9.8\:\rm N/kg\times 4.50\: m}=40.8\:\rm kg$

Answer: c)