Considering the variation of the acceleration due to gravity over the Earth surface, at which location is the weight of a given body maximum?

Introduction / Context:
Weight of a body is the force with which the Earth pulls it toward the centre and is given by W = m * g, where g is the local acceleration due to gravity. The value of g is not exactly the same everywhere on the Earth surface because of rotation and the planet slightly flattened shape. This question asks where on Earth the weight of a given body is maximum, which is equivalent to asking where g has its largest value.

Given Data / Assumptions:
- The Earth is approximated as an oblate spheroid, slightly flattened at the poles and bulging at the equator.- Acceleration due to gravity g varies slightly with latitude.- Weight is proportional to g for a fixed mass.- Effects of local geology are neglected in favour of the general trend with latitude.

Concept / Approach:
There are two main reasons why g varies with latitude. First, the Earth rotation produces a centrifugal effect that reduces the effective gravity more at the equator than at the poles. Second, because of the equatorial bulge, the equator is farther from the Earth centre than the poles, and gravitational force decreases with distance from the centre. Both effects lead to a smaller value of g at the equator and a larger value at the poles. Therefore, for the same mass, weight is maximum at the poles and minimum at the equator.

Step-by-Step Solution:
1. Recall that weight W is given by W = m * g.2. For fixed mass m, weight is directly proportional to acceleration due to gravity g.3. Recognise that at the poles, there is no centrifugal reduction due to rotation because the axis passes through the poles.4. Also recognise that the poles are slightly closer to the Earth centre due to its flattened shape, which increases gravitational pull.5. At the equator, centrifugal effects are maximum and the distance from the centre is slightly larger, both of which reduce the effective g.6. Therefore, g, and hence weight, has its maximum value at the poles.

Verification / Alternative check:
Standard numerical values given in textbooks show g around 9.78 m per s^2 at the equator and about 9.83 m per s^2 at the poles. The difference is small but measurable. Weights of precision objects are sometimes corrected for local value of g in accurate experiments. The larger polar value of g confirms that a body would weigh slightly more at the poles than at the equator.

Why Other Options Are Wrong:
- Equator: Here g is slightly smaller due to greater centrifugal effect and greater distance from the centre, so weight is minimum rather than maximum.- Subtropics: Values of g here are intermediate between equator and poles, not maximum.- Tropics: Similar to subtropics, these latitudes also have intermediate values of g.

Common Pitfalls:
Students sometimes assume weight must be the same everywhere on Earth because mass is constant. Remember that mass and weight are different; mass is intrinsic, while weight depends on the local gravitational field. Another source of confusion is thinking that being closer to the equator somehow increases gravity when the opposite is true once rotation and shape are considered. Keeping these physical reasons in mind helps answer such questions correctly.

Final Answer:
The weight of a body is maximum at the poles of the Earth.