9. you are an engineer and are building metal objects for a science lab that are supposed to hold charge for a long time. the object should not be

a) insulated from everything else
b) smooth
c) sharp and pointed
d) circular

A) insulated from everything else

Explanation:

The objects is supposed to hold the charge for a long time. The only possibility for that to occur is that the charge sticks on the object, and does not flow away from it.

In order for that to make it possible, the object must be insulated from everything else. In fact, if the object is not isolated, it would be able to exchange charge with other objects around: therefore, the charge on the object could be easily transferred to other objects (or otherwise, an opposite-sign charge can be transferred from other objects to the object itself), so the object would not be able to hold its charge.

no. dot product   =0 when vecs at right angles