# Homework Help: Speed and distance

1. Feb 3, 2009

### HellRaiser30

I got a problem and it is that i have an object traveling at a certain rate of speed then another object travelling at another rate of speed hits it from behind to make the first object travel at a higher rate of speed and travel a certain distance from where it was hit till coming to a stop. If i know the distance the first object travelled, after being hit until it came to a stop, and how fast the first object was travelling at, before it got hit, is there an equation that will tell me how fast the second object must have had to been travelling at to hit the first object that distance?

2. Feb 3, 2009

### Astronuc

Staff Emeritus
One also asked:
Well one has to have N equations for N unknowns. In physics, there are the laws of conservation of energy and conservation of momentum. But one must determine if the collisions are elastic or inelastic, and whether or not dissipative forces such as air-resistance or surface-to-surface friction are involved.

Please refer to these examples - http://hyperphysics.phy-astr.gsu.edu/hbase/colsta.html
http://hyperphysics.phy-astr.gsu.edu/hbase/inecol3.html

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