1. What force is required to drag a sack of rice weighing 105 lb if the coefficient of friction is 0.25?
(a) when the force is parallel to the surface,
(b) when the force makes 37° above the horizontal.
2. A piano weighing 600 lb is to be raised to a platform 4 ft high through a plank 10 ft long. If the coefficient of friction is 0.30, what force parallel to the plank will be needed?
The solution shows how to calculate the force needed to drag a sack of rice and to raise a piano to a platform in detail.