A block of mass =4.20 kg slides along a horizontal table with velocity 0=3.50 m/s . At =0 , it hits a spring with spring constant =26.00 N/m and it also begins to experience a friction force. The coefficient of friction is given by =0.250 . How far has the spring compressed by the time the block first momentarily comes to rest? Assume the positive direction is to the right.

answer: the potential energy decreases from 379 j to 243 j

explanation:

for the law of conservation of energy, the total energy in a system must be conserved. the total energy of the system is given by the sum of kinetic (k) and potential (u) energy:

e = k + u

the total energy is e=675 j, and this does not change.

initially, the kinetic energy is k=296 j, so the potential energy is

at the end, the kinetic energy is k=432 j, so the potential energy is

so, we see that the potential energy has decreased from 379 j to 243 j.