Two objects with springs collide

  • Thread starter sarmstrong
  • Start date
  • #1

Homework Statement


Two air blocks with masses 224 g and
130 g are equipped with identical springs
(k = 2490 N/m). The blocks move toward
each other with identical speeds of 1 m/s on a
horizontal air track and collide, compressing
the springs.
Find the maximum compression of the
spring attached to the 224 g mass.

Homework Equations





The Attempt at a Solution


okay so the thing that I don't understand is do the springs split the kinetic energy from the objects equally and if they do I still do not understand what I'm doing wrong.
 

Answers and Replies

  • #2
gneill
Mentor
20,925
2,867

Homework Statement


Two air blocks with masses 224 g and
130 g are equipped with identical springs
(k = 2490 N/m). The blocks move toward
each other with identical speeds of 1 m/s on a
horizontal air track and collide, compressing
the springs.
Find the maximum compression of the
spring attached to the 224 g mass.

Homework Equations





The Attempt at a Solution


okay so the thing that I don't understand is do the springs split the kinetic energy from the objects equally and if they do I still do not understand what I'm doing wrong.

Hi sarmstrong, welcome to Physics Forums.

It's hard to say what you're doing wrong if we can see what it is you're doing... can you show an attempt in detail?

Two identical springs in series behave overall as if they were a single spring with the same spring constant; the compression will be shared, so half can be attributed to each.

Have you considered looking at the problem from the center-of-momentum frame of reference? In that frame the center of collision remains fixed in place, so both masses come to rest at the same instant with both springs as fully compressed as they're going to get. Kinetic and potential energy are conserved ...
 
  • #3
Simon Bridge
Science Advisor
Homework Helper
17,874
1,655
okay so the thing that I don't understand is do the springs split the kinetic energy from the objects equally and if they do I still do not understand what I'm doing wrong.
What would happen if you had two blocks (as above) without springs, but there is a spring attached to the track that they both hit at the same time?

See - during the collision, you have two blocks with a single spring between them.
(careful - the blocks do not have equal and opposite momenta)
 

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