posted by Jim Kirk .
A person doing a chin-up weighs 615.4 N,
disregarding the weight of the arms. During
the ﬁrst 21.0 cm of the lift, each arm exerts
an upward force of 435 N on the torso.
The acceleration of gravity if 9.81 m/s
If the upward movement starts from rest,
what is the person’s speed at this point?
Answer in units of m/s.