A rubber balloon has 200 g of water in it. Its weight in water will be (neglect the weight of balloon)

Options

A. 100 g
B. 200 g
C. 50 g
D. zero

Answer

To find the weight of the rubber balloon containing 200 g of water when it is submerged in water, we can follow these steps:

### Step 1: Understand the weight of the water
The weight of the water inside the balloon can be calculated using the formula:
\[ \text{Weight} = \text{mass} \times g \]
where \( g \) is the acceleration due to gravity (approximately \( 9.81 \, \text{m/s}^2 \)).

Given that the mass of the water is 200 g (which is 0.2 kg), we can calculate the weight of the water:
\[ \text{Weight of water} = 0.2 \, \text{kg} \times 9.81 \, \text{m/s}^2 = 1.962 \, \text{N} \]

### Step 2: Consider the buoyant force when submerged
When the balloon is submerged in water, it experiences a buoyant force equal to the weight of the water displaced. The volume of the water in the balloon is equal to the mass of the water divided by the density of water (approximately \( 1000 \, \text{kg/m}^3 \)):
\[ \text{Volume of water} = \frac{\text{mass}}{\text{density}} = \frac{0.2 \, \text{kg}}{1000 \, \text{kg/m}^3} = 0.0002 \, \text{m}^3 \]

The buoyant force can then be calculated as:
\[ \text{Buoyant force} = \text{Volume} \times \text{density of water} \times g \]
Substituting the values:
\[ \text{Buoyant force} = 0.0002 \, \text{m}^3 \times 1000 \, \text{kg/m}^3 \times 9.81 \, \text{m/s}^2 = 1.962 \, \text{N} \]

### Step 3: Determine the apparent weight
The apparent weight of the balloon when submerged in water is given by the actual weight of the water minus the buoyant force:
\[ \text{Apparent weight} = \text{Weight of water} - \text{Buoyant force} \]
Since both the weight of the water and the buoyant force are equal (1.962 N), we have:
\[ \text{Apparent weight} = 1.962 \, \text{N} - 1.962 \, \text{N} = 0 \, \text{N} \]

### Conclusion
Thus, the weight of the rubber balloon containing 200 g of water when submerged in water is **0 N**.

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