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Free-falling object question

  • Thread starter thomasxc
  • Start date
  • #1
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Homework Statement



an object falls .48 of the total distance in the last one second of its fall. determine total time and height from which it was dropped

Homework Equations



I have no idea. The kinematics, possibly?

The Attempt at a Solution


I have no idea where to begin. Ive tried guess and check with the kinematic equations, to no avail. Please help.

thanks in advance
 

Answers and Replies

  • #2
tiny-tim
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hi thomasxc! :smile:

if the total time is T, apply the standard constant acceleration equations at t = T and t = T - 1 :wink:
 
  • #3
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I'm so rusty at all of this. This is on an intro for my physics class. I am totally lost. I dont have distance, initial or final velocities, only acceleration, T and T-1.
 
  • #4
tiny-tim
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I dont have distance, initial or final velocities, only acceleration, T and T-1.
you do have the initial velocity, it's zero

you also know that s at time t = T-1 is 0.52 times s at time t = T
 
  • #5
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ok. so for displacement, T-1=(.52)t right?

Im lost as to how to set that up.
 
  • #6
tiny-tim
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ok. so for displacement, T-1=(.52)t right?
noooo :redface:

get some sleep, read the question, and try again in the morning :zzz:
 
  • #7
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v=d/t, with that you'll have the velocity at t=1s... Does that help?
 
  • #8
1,137
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I just worked out your problem and you can use s=ut + (at^2)/2 at t=t and t=t-1.

just write 2 eqns and you'll figure out a way easily.
 

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