A sea bird builds its nest on a ledge above the ocean, where it fishes for food. When does the bird have the most potential energy? A. flying at 10 m/s 10 m above the ocean
B. sitting in its nest 20 m above the ocean
C. swimming on the ocean surface at 2 m/s
D. diving for fish 3 m below the ocean surface

Mass is the amount of matter in an object.  weight is the measurement of the pull of gravity on an object.  say for example, you travel to the moon which has a different gravitational field compared to the gravitational field of earth. (gravitational fields: earth = 1, moon = 0.165)  now when you are on the moon, the pull of gravity on you is different than on the earth. and as weight is the measurement of the pull of gravity on an object, that means yes, your weight can and will change on the moon.  however, on the moon, on earth or even on jupiter, the amount of mass inside of you remains the same. meaning your physical mass remains constant.  in conclusion it is possible for your weight to change as your mass remains constant. 

Bis the answerhope it !

Density= mass/volume so 5.1 divided by 4.7 is  5.1 / 4.7 =1.08510638298round to the correct number of sig figs

Hcn is your answer my guy : )