× Didn't find what you were looking for? Ask a question
Top Posters
Since Sunday
Home Q & A Board Biology-Related Homework Help Biochemistry
New Topic  
len5002 len5002
wrote...
Posts: 74
Rep: 0 0
11 years ago
Two objects moving with a speed v travel in opposite directions in a straight line. The objects stick together when they collide, and move with a speed of v/5 after the collision.

1.What is the ratio of the final kinetic energy of the system to the initial kinetic energy? Kf/Ki
2.What is the ratio of the mass of the more massive object to the mass of the less massive object? M/m
Read 6757 times
2 Replies

Related Topics

Replies
wrote...
#1
11 years ago
(M+m)*(v/5) = (M-m)*v or M + m = 5*M - 5*m 0r
4*M = 6*m or M = 1.5*m  Answer for 2)
Answer for 1
Final KE = 0.5*(2.5*m)*(v^2/25) and
Initial KE = 0.5[1.5*mv^2 + m*v^2]
Required Ratio = 1/25 = 0.04
wrote...
#2
11 years ago
The situation you describe is called an INELASTIC COLLISION.  For inelastic collisions, momentum is conserved but kinetic energy is not.  The best that can be said is that KEf will be less than KEi.

If you set the momentum before equal to the momentum after (the minus sign is because they are going towards each other)

m1*v - m2*v = (m1+m2)*v/5

crunch through the math

M1*v(1-1/5) = m2*v(1+1/5)

then m1/m2 = 6/5*5/4 = 3/2
New Topic      
Quick Reply
Explore
Post your homework questions and get free online help from our incredible volunteers
  1253 People Browsing
Start New Topic Take the Tour CoursesNew Study Tools Topics Trending Browse by Textbook
Related Images
  
 7805
  
 253
  
 371
Your Opinion
Which is the best fuel for late night cramming?
Votes: 145
Previous poll results: Which of the following is the best resource to supplement your studies: