Newtons 1st and 2nd Laws Mastering Physics

[C.Me.B]

Homework Statement

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 10% less than the weight of the load. No other forces are acting on the load. Which of the following statements about the elevator are correct? (> 1 can be 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 must be accelerating.

Homework Equations

Newtons 1st and second laws

The Attempt at a Solution

B and F

 

[Doc Al]

Looks good to me.

 

[m2003]

are the correct statements.

Explanation:

According to Newton's first law, an object will remain at rest or in motion with a constant velocity unless acted upon by an external force. Since the only force acting on the load is the tension in the string, and the load is not accelerating, the elevator must be accelerating, making statement F correct.

According to Newton's second law, the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. In this case, since the tension in the string is less than the weight of the load, the net force on the load is less than its weight. This means that the elevator is not an inertial frame of reference, making statement B correct.