A weight is hung from the ceiling of an elevator by a massless string. Under which

circumstances will the tension in the cord be the greatest?

well,if the elevator falls, the tension will be zero

so if the elevator accelerates up fast, count on the string breaking :)

To determine under which circumstances the tension in the cord will be the greatest, we need to consider the forces acting on the weight in different scenarios.

The tension in the cord is equal to the force exerted by the weight. In this case, the weight is hanging from the ceiling of an elevator. Let's consider two scenarios:

1. The elevator is stationary or moving at a constant velocity:
In this scenario, the weight is not accelerating or decelerating. The tension in the cord will be equal to the weight of the object. We can calculate the weight using the formula: Weight = mass x acceleration due to gravity (W = m * g). Since the mass and acceleration due to gravity remain constant in this scenario, the tension will be constant as well.

2. The elevator is accelerating:
In this scenario, the elevator is either moving upward with an acceleration or moving downward with a deceleration. The acceleration could be caused by the elevator starting or stopping or by changing its speed. In these cases, the tension in the cord will be greater than the weight of the object.

When the elevator is accelerating upward, the tension in the cord will be the highest. This is because the weight of the object is being both supported by the tension in the cord and the additional force due to the elevator's acceleration. The total force exerted on the weight is the sum of these two forces, resulting in a higher tension in the cord.

In summary, the tension in the cord will be the greatest when the elevator is accelerating upward.