Mechanics energy problem, inelastic collision. Please help
Favorites|Homepage
Subscriptions | sitemap
HOME > > Mechanics energy problem, inelastic collision. Please help

Mechanics energy problem, inelastic collision. Please help

[From: ] [author: ] [Date: 12-08-18] [Hit: ]
I was going to relate the final total kinetic energy of the system and then subtract the new (stuck) mass to find the total energy loss. That is the only way i can think of to approach the problem, could someone explain how to do it?(Problem) Two football players collide and stick together. One has a mass of 75 kg and is moving to the right at 5 m/s, while the other has a mass of 120 kg and is moving to the left at 1 m/s.......
This was on a test of mine and I can't really figure out how to do it. I was going to relate the final total kinetic energy of the system and then subtract the new (stuck) mass to find the total energy loss. That is the only way i can think of to approach the problem, could someone explain how to do it?



(Problem) Two football players collide and stick together. One has a mass of 75 kg and is moving to the right at 5 m/s, while the other has a mass of 120 kg and is moving to the left at 1 m/s. Find the total loss of kinetic energy in joules.



Please help... I'd really like to figure out how to do this one. thanks

-
KE lost = total initial KE of both - final joint KE

The joint velocity (v) is required after collision .. use conservation of momentum (which applies to any kind of collision.)

As momentum is a vector quantity directions must be taken into account ..
Assuming motion to the right is +ve

Total mom before = joint mom afterwards
(75kg x 5.0m/s→) - (120kg x 1.0m/s←) = (75+120)kg x v
255 = 195v .. .. v = 1.31 m/s

Final KE = ½ (75+120) (1.31)² = 167.30 J

Initial KE = (½ x 75 x 5²) + (½ x 120 x 1.0²) = 997.50 J

KE loss = 997.50 - 167.30 .. .. ►KE loss = 830.20 J
1
keywords: problem,inelastic,energy,help,Mechanics,collision,Please,Mechanics energy problem, inelastic collision. Please help
New
Hot
© 2008-2010 http://www.science-mathematics.com . Program by zplan cms. Theme by wukong .