What is considered a small velocity?

  • Thread starter Thread starter Fellowroot
  • Start date Start date
  • Tags Tags
    Velocity
AI Thread Summary
The discussion revolves around the ambiguity of defining a "small velocity" in physics problems, particularly in the context of an elevator being pulled upwards. Participants express frustration over the lack of specific velocity values, which complicates problem-solving. Suggestions include using average elevator speeds or arbitrary small values like 0.01 m/s as assumptions. The conversation highlights a broader issue in physics where multiple assumptions are often necessary to arrive at a solution, contrasting it with more straightforward mathematical problems. Ultimately, the challenge lies in navigating these assumptions to find a workable answer.
Fellowroot
Messages
92
Reaction score
0

Homework Statement



An elevator is being pulled upwards with an small inital velocity. The elevator cable has a constant tension. After 250 seconds it stops with a gravitational energy of 2400J. Assume the acceleration due to gravity is 10. What is the mass of the elevator?

Homework Equations



PE=mgh

The Attempt at a Solution



Assume what v is then see how high it is then plug into find m.
-------------------------------------------------------------------------------------

Anyway, when a problem says that something is traveling at a small velocity, but does not state what velocity to use, what should we take it as.

This is actually what I don't like about physics. In math if I am given an integral to solve I don't assume anything, I just do it.

I remember in thermodynamics, there was this one problem about a turbine and I tried very very hard to solve it without looking at the solutions manual. Then finally I gave up and looked at the manual and guess what. There was like 3 different assumptions you had to make an order to solve it. Thanks a lot physics.
 
Physics news on Phys.org
Maybe try looking up the average speed of an elevator and take half of that ... or just go with .01 m/s.
 

Thread 'Rolling without slipping on a curved surface'

Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
View full post »

Thread 'Struggling to understand the concept of this question (ice cube in water optics question)'

TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
View full post »

Similar threads

Lift and screw impact velocity
Replies
11
Views
1K
The gravitating of a small mass towards a big mass
Replies
3
Views
2K
How to Apply Derivatives in Physics Problems?
Replies
9
Views
1K
Time it Takes for a Transverse Pulse to Travel a Distance "L" Up a Cable Against Gravity?
Replies
13
Views
1K
Difficult problem in Rotational Mechanics JEE 2017 Comprehension paper
Replies
1
Views
1K
Mechanics: Elevator Accelerating Downward
Replies
10
Views
4K
Finding the period of a pendulum in motion along a curve
Replies
8
Views
2K
Escape velocity of an iron asteroid
Replies
5
Views
2K
What is the velocity of the projectile when it hits the net?
Replies
2
Views
2K
Find the rate of change of velocity
Replies
5
Views
2K

Hot Threads

Recent Insights

Back
Top