A weight of 15 lbs at sea level is suspended

  • Context: Undergrad 
  • Thread starter Thread starter Nornh
  • Start date Start date
  • Tags Tags
    Sea level Weight
Click For Summary
SUMMARY

The discussion centers on calculating the peak load on a wire rope when a 15 lb weight is lifted and dropped 1 ft at sea level. The key conclusion is that the peak tension in the wire depends on the abruptness of the weight's stop, which is influenced by the non-stretching nature of the cable. The conversation highlights that without a defined instant for when the weight stops falling, the problem lacks a precise solution. The deceleration of the weight is gradual, and the peak load cannot be determined without additional information regarding the stopping time.

PREREQUISITES
  • Understanding of basic physics concepts, particularly tension and force.
  • Familiarity with the principles of motion and deceleration.
  • Knowledge of the properties of materials, specifically regarding elasticity and inelasticity.
  • Basic grasp of the implications of instantaneous versus gradual changes in motion.
NEXT STEPS
  • Research the principles of tension in non-stretching cables.
  • Study the effects of deceleration on load calculations in physics.
  • Explore the concept of instantaneous versus gradual forces in mechanical systems.
  • Learn about the dynamics of weight suspension and the factors affecting peak load calculations.
USEFUL FOR

This discussion is beneficial for physics students, engineers, and anyone interested in understanding the dynamics of forces and tension in mechanical systems.

Nornh
Yes, this is in regards to my first question.

A weight of 15 lbs at sea level is suspended by a wire rope that does not stretch. The weight is lifted 1 ft and dropped 1 ft. the initial velocity is "zero". What is the peak lb load on the wire when the weight stops falling?

Thanks for your reply.

This problem does not require a precise answer. I am looking for a plus or minus 5 lb answer. The missing factors that you have mentioned can be assumed in generalities. Is this enough information to come up with an answer?
 
Last edited by a moderator:
Physics news on Phys.org
the peak tension will depend very much on how abruptly the
weight is assumed to stop falling.

in a normal problem this would be influenced by the stretch
of the cable----the less elastic the cable the more abruptly
the object halts and the greater the force.

but your problem is not a problem in physics
since the cable does not stretch, and also it is not well posed since (unless information can
move faster than light) there is no "when"

there is no well-defined instant in time "when the weight'
stops falling"

To see this, imagine that the cable is attached at the top of
the weight. the weight must occupy a physical volume, must
have for example a height, say like 4 inches, between
the bottom and the top where the cable is attached.

when the cable snaps taut it stops the top of the weight
from falling, but the rest of the weight does not know about this
yet and keeps on falling.

so the weight itself must stretch slightly (unless information travels thru the weight at infinite speed)

so the deceleration of the weight is not instantaneous

if any deceleration is instantaneous one can say that the force applied is infinite---but that is not a physical process

so the deceleration of the weight is GRADUAL according to some timetable. If you would somehow indicate the timetable for the weight to stop falling and it would be possible to estimate the peak tension "load" as you ask
 

Similar threads

  • · Replies 20 ·
Replies
20
Views
2K
  • · Replies 3 ·
Replies
3
Views
1K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 35 ·
2
Replies
35
Views
9K
  • · Replies 3 ·
Replies
3
Views
6K
  • · Replies 16 ·
Replies
16
Views
18K
  • · Replies 5 ·
Replies
5
Views
2K
Replies
3
Views
3K
  • · Replies 11 ·
Replies
11
Views
2K
  • · Replies 2 ·
Replies
2
Views
2K