What Is the Recoil Speed of Earth After a Meteorite Collision?

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Homework Help Overview

The discussion revolves around calculating the recoil speed of the Earth following a head-on collision with a meteorite. The problem involves concepts from physics related to momentum and collision types, specifically focusing on a perfectly inelastic collision scenario.

Discussion Character

  • Exploratory, Assumption checking, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore different equations for momentum conservation, questioning the appropriateness of using inelastic versus elastic collision formulas. There is also discussion about the significance of the Earth's mass in relation to the recoil speed and whether to consider the Earth's rotation.

Discussion Status

The discussion includes attempts to apply various formulas, with some participants noting discrepancies in their results. One participant received feedback on significant figures, which led to a corrected answer, although the overall approach remains under scrutiny.

Contextual Notes

Participants are navigating the complexities of collision types and their implications for the calculations, as well as the relevance of significant figures in their final results. There is an acknowledgment of the need for clarity regarding the reference frame for the speed of the satellite involved in the problem.

Idividebyzero
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1.Use 5.98 × 1024 kg as the mass of the Earth.
A 1680 kg meteorite has a speed of 184 m/s
just before colliding head-on with the Earth.
Determine the recoil speed of the Earth.
Answer in units of m/s.



2. (m1+m2)vf=m1v1i+m2v2i



3. used the equation for a perfectly inelastic collision in which the meteor strikes and embeds itself in the Earth causing the Earth to recoil. the Earth being more massive this recoil velocity would be insignificanly small relative to persons on Earth anyways, solved for vf by m1v1i+m2v2i/(m1+m2) taking the Earth to be at rest initially. getting 5.2e-20 which is incorrect. i suppose I am supposed to take kinetic energy into the equations but i don't see how
 
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also tried

V'b= Va(2Ma/Ma+Mb) + Vb(Mb-Ma/Ma+Mb)
V'b=184(2*1680)/(1680 + 5.98e24) + 0
getting V'b=1.03e-19

i don't know maybe i need to take the Earth's rotation into account

nevermind this fails as its for elastic collisions only
 
also figured being a recoil the sign would be opposite, solved using elastic collision i get the same answer. 1.03e-19 but positive and negative incorrect
 
bump i need help
 
The question is that the speed of the satellite is given with respect to the Earth or with respect to the Sun. If it is with respect to the Earth then your method in the first post is correct, but give the result with one more significant digits.

ehild
 
i added more sig figs like you suggested and it was correct. 5.17e-20
 

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