A factory worker pushes a 30.7 crate a distance of 4.0 along a level floor at constant velocity by pushing downward at an angle of 31 below the horizontal. The coefficient of kinetic friction between the crate and floor is 0.26.

What magnitude of force must the worker apply to move the crate at constant velocity?

3 answers

downward? that means he is increasing friction.

Friction force=mu(mg+Force*Sin31)

horizontal force=force*cos31

set them equal, solve for force.
bob is correct, except that you have to subtract the Force*sin(31). It's a poorly worded problem, to say the least.
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