An air-conditioning unit is fastened to a roof that slopes at an angle of 35° above the horizontal. Its weight is a force on the air conditioner that is directed vertically downward. In order that the...

An air-conditioning unit is fastened to a roof that slopes at
an angle of 35° above the horizontal. Its weight is a force on the air
conditioner that is directed vertically downward. In order that the unit not
crush the roof tiles, the component of the unit’s weight perpendicular to the
roof cannot exceed 425 N. (one newton or 1 N, is the SI unit of force. It is
equal to 0.2248 lb.)

(a)




What is the maximum allowed weight of the
unit?

(b)




If
the fasteners fail, the unit slides 1.50 m along the roof before it comes to a
halt against a ledge. How much work does the weight force do on the unit during
its slide if the unit has the weight calculated in part (a)? as we describe in
Section 1.10, the work done by force




on an object that
undergoes a displacement




is