An object is hanging by a string from the ceiling of an elevator. The elevator is moving upward with a constant speed. What is the magnitude of the tension in the string?

The magnitude of the tension in the string is equal to the magnitude of the weight of the object.

The magnitude of the tension in the string is less than the magnitude of the weight of the object.

The tension in the string cannot be determined without knowing the speed of the elevator.

The magnitude of the tension in the string is greater than the magnitude of the weight of the object.

The tension in the string is zero.

The magnitude of the tension in he string is equal to the magnitude of the weight of the object.

Explanation:

According to the Newton's 1st law, An object will remain at rest or in uniform motion in a straight line unless acted upon by an unbalanced force.

In here, the elevator is moving with a constant speed. So the object must have the equal constant speed. Which means, it has a uniform motion. According to Newton's 1st law, the total unbalanced force on the object must be zero. As we know, there are only two forces are on the object and they are,

The tension in string (T), The weight of the object (W).

∴ F = 0

T - W = 0

So to balanced those forces, the magnitude of the tension in the string must be equal to the magnitude of the weight of the object.