Why would his weight be zero at the moment of the fall?

  • Thread starter alaa amed
  • Start date
  • #1
19
0

Homework Statement



A person of weight w is in an upward-moving elevator when the cable suddenly breaks. What is the person's apparent weight immediately after the elevator starts to fall?
 

Answers and Replies

  • #2
20,866
4,545

Homework Statement



A person of weight w is in an upward-moving elevator when the cable suddenly breaks. What is the person's apparent weight immediately after the elevator starts to fall?
How would you personally define the term "apparent weight?"
 
  • #3
19
0
How would you personally define the term "apparent weight?"
I think that's the key to answering the question, though I am not sure I interpreted properly. I think it means the weight relative to the force of gravity that acts on it in particular instance.
 
  • #4
20,866
4,545
I think that's the key to answering the question, though I am not sure I interpreted properly. I think it means the weight relative to the force of gravity that acts on it in particular instance.
That's not correct. It means that, if he was standing on a scale, what the scale would read (i.e., the normal force the person would be exerting on the scale, and, by Newton's 3rd law, the normal force the scale would be exerting on the person). That's the definition of his apparent weight.

So, what is the normal force that the scale is exerting on the person if the elevator cable has been cut?
 
  • #5
19
0
That's not correct. It means that, if he was standing on a scale, what the scale would read (i.e., the normal force the person would be exerting on the scale, and, by Newton's 3rd law, the normal force the scale would be exerting on the person). That's the definition of his apparent weight.

So, what is the normal force that the scale is exerting on the person if the elevator cable has been cut?
I think the person and the elevator would be free falling an so there would be no contact force?
 
  • #6
20,866
4,545
I think the person and the elevator would be free falling an so there would be no contact force?
Yes. That is correct. So what does that mean regarding the "apparent weight" of the person, considering the apparent weight is equal to the contact force.
 
  • #7
19
0
Yes. That is correct. So what does that mean regarding the "apparent weight" of the person, considering the apparent weight is equal to the contact force.
It will be zero! Thank you so much for your help.
I get it now.
 

Related Threads on Why would his weight be zero at the moment of the fall?

Replies
3
Views
26K
  • Last Post
Replies
3
Views
1K
  • Last Post
Replies
15
Views
3K
Replies
2
Views
545
Replies
1
Views
2K
  • Last Post
Replies
4
Views
1K
Replies
3
Views
5K
Replies
3
Views
6K
Replies
4
Views
1K
Top