Inertial frames of reference[an experiment inside an elevator]?

Question

You are conducting an experiment inside an elevator that can move in a vertical shaft. A load is hung vertically from the ceiling on a string. The tension in the string is measured to be exactly equal to the weight of the load. No other forces are acting on the load. Which of the following statements about the elevator are correct?

A.The elevator is an inertial frame of reference.
B.The elevator is not an inertial frame of reference.
C.The elevator may be at rest.
D.The elevator may be moving at a constant velocity upward.
E.The elevator may be moving at a constant velocity downward.
F.The elevator may be accelerating.
G.The elevator must be accelerating.

pls not only answer, i need to understand the concept.
Clear Explanations,

thanx

Answer 1

The answer depends on whether your teacher understands terminological difference between 'force of gravity' and 'weight'. Judging from formulation of this problem. most likely he does not. So I will answer in asumption that

"The tension in the string is measured to be exactly equal to the force of gravity acting on the load"

The following statements are correct::
A C D E



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Note that your question implies that there are two forces acting on the load: tension of string and "weight".

Nope.

Weight of the load is always the force acting not on the load, but on the suspension string, or on the floor. That is why astronauts are said to be weightless.

Answer 2

All answers are correct.

*Of course* The tension in the scale is measured to be the weight of the load. That's the definition of "weight." The reference frame you're in makes no difference, except that the weight and tension in one frame will be different than in another. They're always equal to each other in steady state, however.

Answer 3

An inertial frame of reference (where gravity field is neglected)is a measuring point where motion starts.
A non inertial frame of reference is a measuring point where a Gravity field starts.