- #1
songsteel
- 4
- 0
Homework Statement
A mass 3M moving horizontally with velocity v[itex]_{0}[/itex] on a frictionless surface, strikes head-on and sticks to a horizontal spring system of natural length l and spring constant k with masses M at each end. The spring has negligible mass.
Determine the maximum compression of the spring.
Homework Equations
Conservation of Linear Momentum:
Initial Linear Momentum = Final Linear Momentum
Conservation of Energy:
Initial Kinetic Energy + Initial Elastic Potential Energy = Final Kinetic Energy + Final Elastic Potential Energy
The Attempt at a Solution
3Mv[itex]_{0}[/itex] = (3M + M)Vfinal
Vfinal = [itex]\frac{3}{4}[/itex]v[itex]_{0}[/itex]
At Maximum compression: all the Kinetic Energy would have been converted to Elastic Potential Energy; let x be the maximum compression.
[itex]\frac{1}{2}[/itex](4M)([itex]\frac{3}{4}[/itex]v[itex]_{0}[/itex])[itex]^{2}[/itex] = [itex]\frac{1}{2}[/itex](k)(x)[itex]^{2}[/itex]
[itex]\frac{9}{8}[/itex]Mv[itex]_{0}[/itex][itex]^{2}[/itex] = [itex]\frac{kx^{2}}{2}[/itex]
x = √([itex]\frac{9Mv_{0}^{2}}{4k}[/itex])
According to the answersheet I was given, the final answer should be x = √([itex]\frac{9Mv_{0}^{2}}{20k}[/itex]) instead.
Would really appreciate it if anyone could help me out. Thanks!