A window washer sits in a bosun's chair that dangles from a massless rope that runs over a massless, frictionless pulley and back down to the man's hand. The combined mass of man and chair is m = 97.0 kg. With what magnitude of force F must he pull downward to raise himself at constant speed? F = With what magnitude of force F must he pull downward to raise himself with an upward acceleration a = 1.50 m/s? F = N N