An object just floats in water. If common salt is added into the water,

Options

A. the volume of the object immersed in the liquid decreases.
B. the object sinks
C. the object first sinks and then floats up.
D. cannot be determined

Answer

To solve the problem, we need to understand the relationship between the density of the liquid and the buoyant force acting on the object. Here’s a step-by-step solution:

### Step 1: Understand the initial condition
An object is floating in water, which means the buoyant force acting on it is equal to the weight of the object. The buoyant force (upthrust) is determined by the volume of water displaced by the object.

**Hint:** Recall that an object floats when the buoyant force equals its weight.

### Step 2: Define the buoyant force
The buoyant force (upthrust) can be calculated using the formula:
\[ \text{Buoyant Force} = \text{Density of water} \times g \times \text{Volume of water displaced} \]
Where:
- \( g \) is the acceleration due to gravity.
- The volume of water displaced is equal to the volume of the object that is submerged.

**Hint:** The buoyant force depends on the density of the liquid and the volume of the object submerged.

### Step 3: Effect of adding salt to water
When common salt is added to the water, the density of the water increases. This is because the salt increases the mass of the solution without significantly changing its volume.

**Hint:** Think about how adding mass to a fixed volume changes density.

### Step 4: Analyze the change in buoyant force
As the density of the water increases due to the added salt, the buoyant force acting on the object also increases. This is because the buoyant force is directly proportional to the density of the liquid.

**Hint:** Remember that an increase in density leads to an increase in buoyant force.

### Step 5: Determine the effect on the object
Since the buoyant force has increased while the weight of the object remains the same, the object will experience a greater upward force. This means that the object will displace less water (it will be less submerged) because the increased buoyant force can support the weight of the object with a smaller volume of water displaced.

**Hint:** Consider how the balance of forces changes when the buoyant force increases.

### Step 6: Conclusion
The conclusion is that when salt is added to the water, the volume of the object that is submerged decreases, as the increased buoyant force allows the object to float with less immersion.

**Final Answer:** The volume of the object immersed in the liquid decreases.