James Jumps: Calculating the Fall in Seconds & Meters

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Homework Help Overview

The problem involves calculating the total time and height of a fall experienced by James as he jumps from a window to escape a fire. The scenario includes the use of gravitational acceleration, g = 9.81 m/s², and presents a situation where James has traveled half the height of his fall one second before landing.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the time of the fall, with some suggesting it could be 2 or 3 seconds. There is a debate about whether James is slowing down or speeding up during his fall. Graphing distance versus time is suggested as a way to visualize the problem, although some express confusion about the lack of specific numbers for the graph. The relationship between time and distance is explored, with references to quadratic functions.

Discussion Status

The discussion is ongoing, with various interpretations of the problem being explored. Some participants have attempted calculations and shared results, while others question the completeness and correctness of those attempts. There is no explicit consensus on the answers, and the conversation remains open to further exploration.

Contextual Notes

Participants mention the need for clarity in the problem statement and express frustration over deleted posts. There is also a note about the time of day affecting participation, indicating that some may be fatigued during the discussion.

Creaver
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Homework Statement


To escape the fire which has just declared itself in the building, James jumps through the window. One second before reaching the mattress, he traveled half of the height of fall.

What is the total time of the fall in seconds ?

What is the total height of the fall in meters ?We shall take g = 9,81 m/s ²

The Attempt at a Solution


2 or 3 secondes ?[/B]
I don't need g... Strange...
my attempt...
1/2gt²

0.5 d= 4.9 (t-1)²
t = 3.4142
d = 57.118
 
Last edited:
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Why do you say 2 or 3 seconds? Do you think he is slowing down or speeding up? In what proportions?
(You do need g for rép2 but not for the first part. And do not delete and repost please.)
 
Strange for rep1 because the answer is x,xxxx...

And no, he accelerates...

One second is the half thus 1 * 2 but it isn't that... and i don't understand why...

somebody has deleted my post, not me !
 
Maybe it was deleted because the heading was so non-descriptive.

I suggest you make a graph of distance versus time and mark the last second before impact.
 
But there are no numbers on my graph...
I dont't have the distance traveled during 1 second.
 
The units on the vertical scale do not matter for how the graph looks like. The first part of the problem only involves the time axis. It is the same on the Moon as on Earth.
 
PietKuip said:
The units on the vertical scale do not matter for how the graph looks like. The first part of the problem only involves the time axis. It is the same on the Moon as on Earth.

I don't understand... One second is the only element in this statement and the answer is decimal...

No Google search is necessary ?
 
Try googling for "John, window"...

Better: call the total time T. The distance is a quadratic function of time, on the Moon, on Earth. So:
(T-1)^2 = T^2/2
Do the algebra.
 
T = 3.41421356

Creaver said:
...
my attempt...
1/2gt²

0.5 d= 4.9 (t-1)²
t = 3.4142
d = 57.118
 
  • #10
and for rep2, d = 57.118 is it correct ?
 
  • #11
No, that is not correct. It is incomplete.
 
  • #12
it is 3:35 AM here, I'm tired.

see you tomorrow and big thank you for your patience !
 
  • #13
d = 1/2 gt² ?
No ?

I have 57.118... meters
 
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  • #14
Poor John (or James?).
May he rest in peace.
 

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