Question:

Ice on land mass melting into ocean, due to global warming, is estimated to be around $1.3 \times 10^{15}\text{ kg}$ per year. The density of sea water is $1025\text{ kg}\cdot\text{m}^{-3}$. Assuming that the melting rate of ice remains constant and the effective surface area covered by the oceans is $3.6 \times 10^{14}\text{ m}^2$, the estimated average rise in sea level (in m) in the next 75 years will be closest to

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Using quick approximation:
$1025 \approx 1000 = 10^3$.
$V \approx 9.75 \times 10^{13}\text{ m}^3$.
$h \approx \frac{9.75 \times 10^{13}}{3.6 \times 10^{14}} = \frac{9.75}{36} \approx 0.27\text{ m}$, which points directly to 0.25 m.
Updated On: Jun 16, 2026
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The Correct Option is A

Solution and Explanation

Step 1: Understanding the Question:
The problem asks for the vertical rise in the sea level over a span of 75 years, given the rate of ice melting on land, the density of seawater, and the total surface area of the oceans.

Step 2: Key Formula or Approach:
- Find the total mass of melted ice in 75 years.
- Convert this mass to volume using the density of seawater:
\[ V = \frac{M}{\rho} \]
- Find the rise in height $h$ by dividing the volume by the ocean surface area $A$:
\[ h = \frac{V}{A} \]

Step 3: Detailed Explanation:

• The rate of ice melting is $R = 1.3 \times 10^{15}\text{ kg/year}$.

• Over a period of $t = 75\text{ years}$, the total mass of water added to the oceans is:
\[ M_{\text{total}} = R \times t = (1.3 \times 10^{15}\text{ kg/year}) \times 75\text{ years} \]
\[ M_{\text{total}} = 9.75 \times 10^{16}\text{ kg} \]

• Now we convert this mass of water into equivalent volume $V$ using the density of seawater $\rho = 1025\text{ kg/m}^3$:
\[ V = \frac{M_{\text{total}}}{\rho} = \frac{9.75 \times 10^{16}\text{ kg}}{1025\text{ kg/m}^3} \]
\[ V \approx 9.512 \times 10^{13}\text{ m}^3 \]

• The rise in sea level $h$ is the volume divided by the surface area of the oceans $A = 3.6 \times 10^{14}\text{ m}^2$:
\[ h = \frac{V}{A} = \frac{9.512 \times 10^{13}\text{ m}^3}{3.6 \times 10^{14}\text{ m}^2} \]
\[ h \approx 0.264\text{ m} \]

• Looking at the options, $0.264\text{ m}$ is closest to $0.25\text{ m}$.



Step 4: Final Answer:
The estimated average rise in sea level is closest to 0.25 m.
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