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28. A person pushes a 14.5-kg lawn mower at constant speed with a force of 88.0 N directed along the handle, which is at an angle of 45.0 degrees to the horizontal. Calculate (a) the horizontal retarding force on the mower, then (b) the normal force exerted vertically upward on the mower by the ground, and (c) the force the person must exert on the lawn mower to accelerate it from rest to 1.5 m/s in 2.5 seconds (assuming the same retarding force).

30. One 3.0-kg paint bucket is haning by a massless cord from another 3.0-kg paint bucket, also hanging by a massless cord. (a) If the buckets are at rest, what is the tension in each cord? (b) If the two buckets are pulled upward with an acceleration of 1.60 m/s^2 by the upper cord, calculate the tension in each cord.

32. A window washer pulls herself upward using the bucket-pulley apparatus. (a) How hard must she pull downward to raise herself slowly at constant speed? (b) If she increases this force by 10 percent, what will her acceleration be? The mass of the person plus the bucket is 65 kg.