Question

) the length of a rectangle is increasing at a rate of 8 cm/s and its width is increasing at a rate of 3cm/s. when the length is 20 cm and the width is 10 cm, how fast is the area of the rectangle increasing?

Answer 1

It’s a little surprising that this question didn’t come up earlier.  Unfortunately, there’s no intuitive way to understand why “the energy of the rest mass of an object is equal to the rest mass times the speed of light squared” (E=MC2).  A complete derivation/proof includes a fair chunk of math (in the second half of this post), a decent understanding of relativity, and (most important) experimental verification.