Final answer:
When an object is lowered into water, the water level decreases because the object displaces less water compared to when it was floating. This happens because the weight of the object is greater than the buoyant force acting on it.
Step-by-step explanation:
When an object is placed in water, it displaces some of the water, causing the water level to rise. However, the object also experiences an upward force called buoyancy, which opposes the force of gravity. This buoyant force depends on the volume of the object and the density of the water.
When an object is lowered into the water, the water level decreases because the object displaces less water compared to when it was floating. This happens because the weight of the object is greater than the buoyant force acting on it, causing it to sink. Therefore, the water level appears to go down when the object is lowered.