Question on this problem

  • Thread starter lefthand
  • Start date
  • #1
8
0
Suppose the wheel is rotated at a constant rate so that the mass has an upward speed of 4.07 m/s when it reaches a point P. At that moment, the wheel is released to rotate on its own. It starts slowing down and eventually reverses its direction due to the downward tension of the cord. What is the maximum height, h, the mass will rise above the point P?
h =m

my question is what formula should i use? i've been using 1/2mv^2+1/2lw^2=mgh.....but i haven't been getting the right answer...if anyone knows has a hint that would help i would like to use it :)
 

Answers and Replies

  • #2
Redbelly98
Staff Emeritus
Science Advisor
Homework Helper
Insights Author
12,121
160
It appears that you are using the correct formula (conservation of energy), though without seeing the figure or your actual work I cannot be 100% sure. Here are a few things that you might check:

1. When you calculate I, do you use the mass of the wheel -- and not the rising mass?
2. Is the wheel like a solid disk, or is most of its mass in the rim? That will affect what I is, in terms of the wheel's mass and radius.
3. Sometimes a problem tells you the diameter of a wheel, and students can mistakenly use that instead of the radius to calculate I, or to relate v and ω to each other.

If you didn't make any of those mistakes I listed, then please post your work.
 

Related Threads on Question on this problem

  • Last Post
Replies
8
Views
577
  • Last Post
Replies
9
Views
504
  • Last Post
Replies
2
Views
835
  • Last Post
Replies
11
Views
3K
  • Last Post
Replies
2
Views
2K
  • Last Post
Replies
5
Views
571
Replies
2
Views
1K
  • Last Post
Replies
1
Views
390
  • Last Post
Replies
3
Views
1K
  • Last Post
Replies
1
Views
2K
Top