What is the final speed of the truck and car after an elastic collision?

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Homework Help Overview

The discussion revolves around an elastic collision problem involving a 750-kg car and a 1790-kg truck. The car is initially at rest and is struck by the truck, which is moving at a speed of 16.0 m/s. Participants are attempting to determine the final speeds of both vehicles after the collision.

Discussion Character

  • Exploratory, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants are discussing the application of conservation of momentum and kinetic energy principles in elastic collisions. There are attempts to set up equations based on these principles, but some participants express confusion regarding the calculations and the method used.

Discussion Status

The discussion is ongoing, with participants sharing their equations and calculations. Some guidance has been offered regarding the potential use of the coefficient of restitution to simplify calculations. However, there is no explicit consensus on the correct approach, as some participants are still questioning their methods and results.

Contextual Notes

Participants are grappling with the accuracy of their calculations and the setup of their equations. There is mention of a potential error in the method used, indicating that assumptions or interpretations of the problem may be under scrutiny.

godkills
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A 750- kg car stopped at an intersection is rear-ended by a 1790- kg truck moving with a speed of 16.0 m/s

If the car was in neutral and its brakes were off, so that the collision is approximately elastic, find the final speed of the truck.

Find the final speed of the car.


256 = (28640 -750v2)2 / 17902 + .42v22

v2 = 22.51
v1 = 6.757

i don't know what am i doing wrong but i get wrong answer.
 
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I can't really understand what you have done. Explain it...
 
1790kg x 16 m/s = 1790s1 + 750 s2 where s1 and s2 is velocity of truck and car after collision.

s1=(28640 -750s2)/1790

1/2(1790)(16)^2=1/2(1790)(s1)^2 +1/2(750)(s2)^2

196=s1^2+0.42s2^2 equation number 2

then i plugged in s1 into equation number 2
 
The method is fine, there must be a problem in calculation. If you want to ease the calculations then use coefficient of restitution.
 
s2=21.51
s1=6.56

new ones still wrong i seriously don't know why i performed the calculations correctly
 

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