Reference Frames: Understanding Elevator Motion

[Bostonpancake0]

someone please help me out with this question:

You are in an elelvator that is able to travel up and down a mineshaft. a load is hung from the ceiling inside the elevator on a massless string. You find that the tension in the rope is 10% less than that of the weight force of the load. what can be said about the elevator?;

1./ it's an inertial reference frame
2./it's a non-inertial refernce frame
3./it's moving up at a constant velocity
4./moving down with a constant velocty
5./must be accelerating

I'm thinking 2./ and 5./ but definitely not sure. Could someone walk me through reference frames in this context and help me understand what is going on?

 

[haruspex]

your answers are correct. You must have had some basis for choosing those - what was your reasoning? What is meant by an inertial frame?

 

[Bostonpancake0]

Well I figured that the elevator is a non inertial frame of reference as there must be some kind of acceleration. But if that's so I thought the Newtonian mechanics would break down, and the only thing that could cause tension in the string to be different to the weight load would be a force applied on the rope in the elevator (e.g the load being pulled up or down relative to the elevator). So I thought that the motion of the elevator would have no effect on the string in the elevator

 

[haruspex]

Do you understand that when the question mentions 'weight force load' it means what the force would have been had the elevator been stationary?
When an elevator starts to go up, what do you notice about the forces on your legs?

 

[Nickie]

I can provide some insight into this situation. Reference frames are used to describe the motion of an object relative to a fixed point or observer. In this case, the elevator is the reference frame and the load is the object in motion.

Based on the given information, we know that the elevator is traveling up and down a mineshaft, which means it is not remaining at a constant position. This suggests that the elevator is a non-inertial reference frame, as it is accelerating due to the changing velocity.

Additionally, we know that the tension in the rope is 10% less than the weight force of the load. This indicates that the load is experiencing a net downward force, which could be due to the acceleration of the elevator or the force of gravity pulling the load down.

Considering all of this information, we can conclude that the elevator is indeed accelerating (option 5./). However, it is important to note that the elevator could be accelerating in either direction (up or down) depending on the specific scenario. Therefore, we cannot say for certain if it is moving up at a constant velocity (option 3./) or moving down with a constant velocity (option 4./).

In summary, the elevator in this scenario is a non-inertial reference frame due to its acceleration, and the load is experiencing a net downward force. The direction of the elevator's acceleration cannot be determined with the given information.