An ideal spring with a force constant (spring constant) of 15 N/m is initially compressed by 3.0 cm from its uncompressed position. How much work is required to compress the spring an additional 4.0 cm?

Work done to stretch the spring additional 4 cm is 0.09 J

Explanation:

We have given spring constant of the sprig k = 15 N/m

We have to find the work require to stretch the spring additional 4 cm

Initially spring is compressed to 3 cm that is ; x = 3 cm = 0.03 m

So initial energy

Now spring is compressed to additional 4 cm

So final energy

So work done to compress additional 4 cm is 0.036 - 0.027 = 0.009 J

he . if i may ask what i your question exactly?

explanation:

the minimum amperage that the current in this wire would have to have so that its weight is completely supported by the magnetic force due to earth's field, assuming that no other forces except gravity act on it