22. IP A school yard teeter-totter with a total length of 5.2 m and a mass of 36 kg is pivoted at its center. A 18 kg child sits on one
end of the teeter-totter. (a) Where should a parent push verti
cally downward with a force of 210 N in order to hold the
teeter-totter level? (b) Where should the parent push with a
force of 310 N? (c) How would your answers to parts(a) and (b)
change if the mass of the teeter-totter were doubled? Explain.