Bucket being lowered vertically by a rope

[e-zero]

Homework Statement

A 12.0kg bucket is lowered vertically by a rope in which there is 163N of tension at a given instant. What is the acceleration of the bucket? Is it up or down?

Homework Equations

Ft - mg = ma

The Attempt at a Solution

I solved for 'a' and got a = 3.78 m/s^2, but how do I figure out which direction?

 

[voko]

With respect to the bucket, can the force of tension be upward? Downward?

 

[e-zero]

upward

 

[voko]

What is upward in terms of signs? Positive or negative?

 

[nothingkwt]

If the bucket is being lowered carefully would you say that it is accelerating upwards?

 

[e-zero]

I would say that if its lowering at a constant speed then there is no acceleration.

Also, I would say that, if anything, since its moving downwards it would be decelerating. Which I guess is the same as accelerating upwards??

 

[nothingkwt]

I would say that if its lowering at a constant speed then there is no acceleration.

Also, I would say that, if anything, since its moving downwards it would be decelerating. Which I guess is the same as accelerating upwards??

Well you are right but there was no mentioning the fact that the bucket was being lowered at a constant speed. If that were the case then that means that mg = Ft which is not true in this case because it is not being lowered at a constant speed.

As for direction the answer to the question implies that the bucket is being pulled up and yet the question states that it is being lowered, so either I got confused or the question is misleading.

 

[e-zero]

How could mg = Ft if it were lowered at a constant speed?? That would indicate that the bucket is at rest.

 

[Doc Al]

How could mg = Ft if it were lowered at a constant speed?? That would indicate that the bucket is at rest.

No, it would just mean that the net force is zero and thus the acceleration, not the speed, is zero. The speed could be anything, as long as it remained constant.

 

[e-zero]

Damn, I missed again :/