A student is about to do a push-up. Her

center of gravity lies directly above P on the
floor, which is 1.1 m from her feet and 0.4 m
from her hands.
If her mass is 55 kg, what is the force exerted by the floor on her hands? The acceleration of gravity is 9.81 m/s
2
.

1 answer

While stationary, the total moment about an axis through her toes is zero.

Her hands are 1.5 m from her toes. Her center of mass is 1.1 m from her toes.

F*1.5 - M*g*1.1 = 0

F = (1.1/1.5)M*g = 395 Newtons