In order to know how long it has been falling for you take the final velocity "49m/s" and divide it by the acceleration "9.8m/s" and get 5, since you have been using seconds in the calculations the answer is 5 seconds. (Fun fact, it is actually 9.82m/s per second since it accelerates and they rounded it down.)
#6 - Lower frequencies correspond to <em>longer</em> wavelengths.
#7 - To change the pitch of a sound, you have to change its <em>frequency</em>.
I would say that the answer is 4.) because if she does most of cooking on the stove, that would allow us to make the assumption that she is using heat and therefore requires and apparatus that conducts heat. Copper is also a metallic that is known to be conductive.
I would guess anything that is black? black absorbs there most light energy. that's is why a black car in the sun will always be hotter inside than a white car.
Friction is a force that oppose other forces and can slow them down
