NICET - Highway Construction Inspection Practice Exam

What is the weight of the block when submerged in water, if its volume is 2 cubic feet and its weight in air is 300 pounds?

1. 175.2 lb

2. 300 lb

3. 124.8 lb

4. 62.4 lb

The correct answer is: 175.2 lb

To determine the weight of the block when submerged in water, we need to use the principle of buoyancy, specifically Archimedes' principle. This principle states that a body submerged in a fluid experiences a buoyant force equal to the weight of the fluid displaced by the body. In this case, the block has a volume of 2 cubic feet. The weight of the water displaced by the block can be calculated using the density of water, which is typically 62.4 pounds per cubic foot. Therefore, the weight of the water displaced by the block is: Weight of displaced water = Volume of block × Density of water = 2 cubic feet × 62.4 lb/cubic foot = 124.8 pounds. When the block is submerged, the weight of the block in water is calculated by subtracting the buoyant force (the weight of the displaced water) from the weight of the block in air: Weight in water = Weight in air - Weight of displaced water = 300 pounds - 124.8 pounds = 175.2 pounds. This calculation shows that when submerged, the block effectively weighs 175.2 pounds due to the upward buoyant force exerted by the water. Thus