17. a 25 kg block is initially at rest on a rough, horizontal surface. a horizontal force of 75 n is required to set
the block in motion, and a 60 n force is required to keep it in motion at a constant speed once it is moving.
what are the coefficients of static and kinetic friction?

Aheavy boy and a lightweight girl are balanced on a massless seesaw. the boy moves backward, increasing his distance from the pivot point. what happens to the seesaw? it is impossible to predict without knowing additional information. the side the boy is sitting on will tilt downward. the side the girl is sitting on will tilt downward. nothing; the seesaw will remain balanced.