Question

An early submersible craft for deep-sea exploration was raised and lowered by a cable from a ship. When the craft was stationary, the tension in the cable was 7000 N. When the craft was lowered or raised at a steady rate, the motion through the water added an 1800 N drag force.
(a) What was the tension in the cable when the craft was being lowered to the seafloor?
(b) What was the tension in the cable when the craft was being raised from the seafloor?

Answer 1

Answer:

a) 5200 N  b) 8800 N

Explanation:

a) tension in the cable when it was being lowered to the sea floor = weight of the object which acts downward ( equals the tension in the cable when the craft was stationary in opposite direction)  - the drag force which will act upward =  7000 - 1800 = 5200 N

b) tension in the cable when the craft was being raised since the tension will act upward and the drag force and the weight will act downward = 7000 + 1800 = 8800 N