(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A block of mass m1 = 2 kg slides along a frictionless table with speed 10 m/s. Directly in front of it, and moving in the same direction with a speed of 3 m/s is a block of mass m2 = 5kg. A massless spring with spring constant k = 1120 N/m is attached to the second block. The spring is compressed a maximum amount x. What is the value of x?

2. Relevant equations

m1v1 + m2v2 = m1vf1 + m2vf2

KEi = KEf + 1/2kx^2

3. The attempt at a solution

I knew that there would be a maximum compression of the spring when the first block has velocity = 0 m/s. I used cons. of momentum :

(2 kg)(10 m/s) + (5 kg)(3 m/s) = (5 kg)(Vf) to find Vf = 7 m/s

then used cons. of energy:

(0.5)(5 kg)(7 m/s)^2 = 1/2(1120)x^2

and got x = 0.4677 m

but the correct answer is 0.250 m

can anyone help me find the correct answer

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Conservation of momentum & energy

**Physics Forums | Science Articles, Homework Help, Discussion**