Aforce of 14 lb is required to hold a spring stretched 4 in. beyond its natural length. how much work w is done in stretching it from its natural length to 10 in. beyond its natural length?

Explanation:

14 lb force is required to stretch the spring by 4 inch distance

So we have

stretch in the spring is given as

now we will have

Now we need to find the work to stretch it by x = 10 in = 0.254 m

so we have

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

wavelength divides in half and speed stays the same.