A custodian pushes a 138 kg box across a level floor. The box moves at a constant velocity. The custodian pushes horizontally on the box with a force of 853 Newtons, what must be the friction force experienced by the box in Newtons?

Suppose a force of 60 n is required to stretch and hold a spring 0.1 m from its equilibrium position. a. assuming the spring obeys hooke's law, find the spring constant k. b. how much work is required to compress the spring 0.5 m from its equilibrium position? c. how much work is required to stretch the spring 0.6 m from its equilibrium position? d. how much additional work is required to stretch the spring 0.1 m if it has already been stretched 0.1 m from its equilibrium? a. kequals 600