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Newton's Thrid Law Question

  • Thread starter Paymemoney
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  • #1
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Homework Statement


I have a mass of 65kg. If I jump off a 120-cm-high table, how far toward me does Earth move during the time i fall?

Homework Equations


F=ma


The Attempt at a Solution


Had a shot using f=ma but couldn't get the answer.

P.S
 

Answers and Replies

  • #2
kuruman
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What is the force that you exert on the Earth? Knowing this force, can you calculate the Earth's acceleration?
 
  • #3
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ok, i had another try of this question and i went W=mg which is 68 * 9.8 i get the force 666.4N then what should i do next?
 
  • #4
kuruman
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ok, i had another try of this question and i went W=mg which is 68 * 9.8 i get the force 666.4N then what should i do next?
If 666.4 N is the force that the Earth exerts on you, what the force that you exert on the Earth?
 
  • #5
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the same because of Newton's Third Law, so i found the acceleration by doing the following:
Mass of Earth is 5.97 * 10^24 (according to the book)

637 = (5.97 *10^24)a
a=1.06*10^-22 m/s^2

now how do i find how far toward me does Earth move during the time i fall?
 
  • #6
kuruman
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the same because of Newton's Third Law, so i found the acceleration by doing the following:
Mass of Earth is 5.97 * 10^24 (according to the book)

637 = (5.97 *10^24)a
a=1.06*10^-22 m/s^2

now how do i find how far toward me does Earth move during the time i fall?
How many seconds does it take you to fall 1.20 m to the surface of the Earth with an acceleration of 9.8 m/s2? In that same amount of time the Earth "falls" towards you with an acceleration of 1.06x10-22 m/s2. Use the kinematic equation to find the distance.
 
  • #7
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thanks i know how to do it now.
 

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