At which of the following locations on Earth is the weight of an object the maximum due to variation in gravitational acceleration?

Introduction / Context:

This question examines understanding of how the weight of an object varies with location on the Earth due to changes in gravitational acceleration. Although the mass of an object remains constant, its weight can change slightly from place to place because of the shape of the Earth and the effect of rotation. This concept is important in physics, geodesy and earth science and is frequently asked in general science sections of competitive exams.

Given Data / Assumptions:

• Weight depends on gravitational acceleration g, where weight = mass * g.
• The Earth is not a perfect sphere; it is an oblate spheroid, slightly flattened at the poles and bulged at the equator.
• The Earth rotates about its axis, producing a centrifugal effect strongest at the equator and zero at the poles.
• We compare locations such as poles, equator, and specific latitudes like the Tropic of Cancer and Tropic of Capricorn.

Concept / Approach:

Two main factors influence the value of g on the Earth surface: the distance from the centre of the Earth and the centrifugal effect due to rotation. At the equator, the radius of the Earth is slightly larger and the centrifugal force is maximum, which effectively reduces the felt gravitational acceleration. At the poles, the radius is slightly smaller and there is no centrifugal effect because the rotation axis passes directly through the poles. Thus gravitational acceleration is maximum at the poles and minimum at the equator, making weight maximum at the poles.

Step-by-Step Solution:

Verification / Alternative check:

Standard physics tables show approximate values such as g at poles around 9.83 m/s^2 and g at equator around 9.78 m/s^2. Even though the difference is small, it confirms that gravitational acceleration is greater at higher latitudes. Because weight is directly proportional to g, the location with highest g must give highest weight. This numerical comparison verifies that the poles are the correct answer.

Why Other Options Are Wrong:

At the equator, the combination of larger radius and maximum centrifugal effect reduces effective gravity, so weight there is slightly less, not more. The Tropic of Cancer and Tropic of Capricorn are intermediate latitudes where g is between equatorial and polar values, so weight is not maximum there. The option stating that weight is the same at sea level anywhere on Earth ignores these well known variations in g and is therefore incorrect.

Common Pitfalls:

Learners often assume that weight is identical everywhere on Earth since mass is constant, overlooking the dependence on local gravitational acceleration. Another common error is to think that the equator should have the greatest gravity because it is a larger circle, which is the opposite of the truth. Some may also confuse concepts like apparent weightlessness with actual changes in g. Careful attention to the role of Earth rotation and shape helps avoid these misunderstandings.

Final Answer:

The weight of an object on Earth is maximum At the poles.