Final answer:
The force required to lift a 5.00 kg sack at constant velocity is 49 N, equal to its weight. The work done by this force lifting the sack through 15.0 m is 735 J.
Step-by-step explanation:
The question at hand involves calculating the force required to lift a bag of flour as well as the work done by this force.
(a) If the sack is lifted at a constant speed, the force required to lift the sack is equal to the weight of the sack, which is the mass of the sack multiplied by the acceleration due to gravity (g = 9.8 m/s2). Thus, the force F required is F = mass × gravity = 5.00 kg × 9.8 m/s2 = 49 N.
(b) The work done on the sack by the lifting force while moving through a height of 15.0 m is calculated as Work (W) = force × distance, which translates to W = 49 N × 15.0 m = 735 J (joules).