Question 9

[dnpgr16513]

I don't understand this question. I was given the impression that the electrical current was given AFTER the spring was compressed.

Substance Q42 is fully expanded and then contracts in response to a 5.0 amp current. Which of the following best represents the conversion of energies in the process described?


When the spring is fully EXPANDED, the spring is at maximal POTENTIAL ENERGY. When the spring is COMPRESSED, the spring is at KINETIC energy.

^ Therefore, from this logic, I reasoned that answer A was the only correct answer.

Why am I wrong?

Thanks.

[jsfkt78927]

how would the spring be compressed without any energy put into the system?

answer: it cant (unless youre harry potter, or maybe hermione granger, from the looks of your name dnpgrl6513 i'm assuming youre a girl)

secondly, you have your concept of potential energy mixed up.

Potential energy means stored energy. (review your min and max KE and Potential energy of springs and pendulums, or just keep reading: Max KE is at minimum displacement and max Potential energy is at maximal displacement.)(we've seen questions like these already, but they've dealt with min/max acceleration and velocity)
When the spring is not compressed, there is no potential energy. Only when its fully compressed (or even a little bit) does it have potential energy.

then in between obtaining potential energy, there is mechanical energy.

[walkerahl5194]

Another question (of the many) where gold standard fails miserably at testing a topic. A compressed or expanded spring both have stored potential energy. The only difference is the direction of the restorative force. The magnitude of the potential energy is the same. Fully expanded to fully compressed contains the same amount of potential energy, just the directions are in opposite directions, thus *** the answer.

I can't believe I'm wasting my time with this material. Too many of my brain cells have already died because of this material. I advice you to save your time, money, and brain cells.

[dltkdgn896512]

[dltkdgn896512]

at least i learned what mechanical energy is