Final answer:
The tension in the rope when lowering a load into a well and moving downward with constant velocity is equal to the weight of the supported mass.
Step-by-step explanation:
When you are lowering a load into a well with a rope and it moves downward with constant velocity, the tension in the rope is equal to the weight of the load. According to Newton's second law, since the load is moving with constant velocity, the net force acting on it must be zero. This implies that the tension in the rope supporting the load must be equal to the gravitational force pulling it downward, which is its weight (mg, where m is the mass of the load and g is the acceleration due to gravity).