Acceleration in a fluid with specific gravity

[pkamensky]

[An object with mass 30 kg and specific gravity 3.6 is placed in a fluid whose specific gravity is 1.2. Neglecting viscosity, which of the following is true?


A. The acceleration of the object is 1\3g and its apparent weight is 100N
B. The acceleration of the object is 2\3g and its apparent weight is 100N
C. The acceleration of the object is 1\3g and its apparent weight is 200N
D. The acceleration of the object is 2\3g and its apparent weight is 200N



I believe the weight is 100N, but do not know the grams or why

 

[ideasrule]

"g" is not grams; it's the acceleration due to gravity. To start this problem, draw a free-body diagram on the mass and label all forces. Write out Newton's second law, then solve for acceleration.

By the way, in case you didn't know, "apparent weight" is just the net external force on the mass.