Final answer:
When an elevator accelerates upward, the tension in the cable increases as it must overcome both the gravitational force and the force needed for upward acceleration.
Step-by-step explanation:
In an elevator hanging from a single cable, when the elevator is accelerating upward, the tension in the cable increases. This is because the tension must not only support the weight of the elevator but also provide the extra force needed to accelerate it upwards. To calculate the actual tension in the cable during upward acceleration, you can use the following formula where T is the tension, m is the mass of the elevator, g is the acceleration due to gravity, and a is the upward acceleration of the elevator:
T = m(g + a).
For example, if an elevator with a mass of 1700 kg accelerates upward at 1.20 m/s², the tension in the cable can be calculated by first finding the gravitational force (mg) and then adding the force of acceleration (ma). So, the correct answer to what happens to the tension when an elevator accelerates upward is: A) Tension increases.