Block A is released from rest at the center of a tank of water. The block accele
ID: 1873643 • Letter: B
Question
Block A is released from rest at the center of a tank of water. The block accelerates upwara 1. At the instant the block is released, is the magnitude of the buoyant force on block A greater than, less than, or equal to the magnitude of its weight? Explain your reasoning When block A reaches the surface, it is observed to float at rest as shown in the diagram on the right. In this final position, is the buoyant force on block A greater than, less than, or equal to its weight? Explain your reasoning If 90% of block A lies below the surface of the water in its final position, then what is the density of block A? Explain/show your reasoning. 2. Final position of block A 3. Imagine that block A were released in the center of a tank filled with a fluid that is twice as dense as water. 4. Describe what will happen to block A after it is released. 5. Calculate the percentage of block A that is submerged after block A comes to rest Explain/show your reasoningExplanation / Answer
1) If the object is completely immersed, its upper half will also experience a pressure in the downward direction. The pressure pushing the object downwards will be lesser than the pressure upwards because of the difference in depth. Therefore, net buoyant force will be greater than weight of the object.
2) The object floats at rest if the buoyant force is equal to the weight of the object that was acting downward.
3) If 90% is submerged, it means 9/10 th is submerged and 1/10th is above the surface
volume submerged = 9/10*V
NOW WEIGHT = BUOYANCY
V*rho*g = 9/10*V*1000*g
rho = 900 kg/m3
4) Now, since gravity and the weight of the object are fixed, an increase in density means a decrease in the submerged volume. The surface above the water level will increase.
5) Using the same concept as in question (3)
6) If block B doesn't move, it means all the forces acting on it are balanced. the upward force on the lower face in properly balanced by downward acting pressure and gravity.
7) If block b is neutral and is acted with same force on each side then net buoyancy force on block A is more than that of block B.