Afree vibration test is conducted on an empty elevated water tank. a cable attached to the tank applies a lateral (horizontal) force of 35 kips and pulls the tank horizontally by 2 in. the cable is suddenly cut to result in a free vibration of the tank system. the weight of the empty tank is 15 kips. required: (a) the natural period of undamped vibration of the tank when it is empty. (b) the natural period of undamped vibration of the tank when it is full of water. the weight of water required to fill the tank is 72 kips.

answer;

d. are made mostly of liquid

explanation;

-the general   composition and structure planets includes; they have a thick gas and liquid layer covering a small,solid core. mostly the gases are hydrogen and helium atmosphere and layers of liquid hydrogen. for instance neptune and uranus are examples of the outer planets, they have a core covered by ice and ammonia.

-neptune's atmosphere is hydrogen and helium with a bit of methane so there is no oxygen to breath and the interior is made up of frozen water and ammonia with a rock and iron core. thus, there is no liquid water or solid surface to survive.