
#1
Jan212, 07:47 PM

P: 25

1. The problem statement, all variables and given/known data
A 150 kg cart moving at 13 m/s east collided with a 420 kg wagon moving at 5.0 m/s east. The cart rebounded westward with a speed of 3.0 m/s . What was the speed of the wagon after the collision? Observe standard Cartesian coordinates. 2. Relevant equations KE1+KE2=KE1'+KE2' conservation of momentum conservation of kinetic energy in elastic collisions 3. The attempt at a solution (0.5)(150)(13)^{2}+(0.5)(420)(5)^{2}=(0.5)(150)(3)^{2}+(0.5)(420)v^{2} v=9.0m/s Answer as given is 11m/s 



#2
Jan212, 09:52 PM

P: 607

the problem itself doesn't say that the collision is elastic. so just use conservation of momentum here.




#3
Jan212, 10:29 PM

P: 1,135

Conservation of kinetic energy is valid only when coefficient of restitution(e) is 1 here its not specified, so you must use momentum conservation. ALSO: if e is given and is ≠1 then you may use: (v_{2}  v_{1}) = e(u_{1}  u_{2}) 


Register to reply 
Related Discussions  
Ellastic collision between a frame and projectile  Introductory Physics Homework  7  
Giancoli, 3rd Ed, pr. 55: Ellastic collision. Solved, but is there easier way?  Introductory Physics Homework  2  
...of which i thought was an ellastic collision problem  Introductory Physics Homework  3  
ellastic collisions  Introductory Physics Homework  7  
ellastic collisison  Introductory Physics Homework  4 