Weight variation with location: If g1 and g2 are the local gravitational accelerations at two mountain locations A and B respectively, by what factor will the weight of a body change when transported from A to B (assume mass remains constant)?

Difficulty: Easy

Correct Answer: g2 / g1

Explanation:


Introduction / Context:

In engineering mechanics and physics, the weight of a body is the gravitational force acting on its mass. Although the mass of a body is invariant with location, its weight can change slightly from place to place because the local acceleration due to gravity varies with altitude, latitude, and underlying geology.


Given Data / Assumptions:

  • Two locations: mountain A with gravitational acceleration g1 and mountain B with gravitational acceleration g2.
  • The same body (constant mass m) is moved from A to B.
  • Air buoyancy and other minor effects are neglected.


Concept / Approach:

Weight W is defined as W = m * g. For the same mass m at different locations with acceleration g, weight scales directly with g. Therefore, the ratio of the new weight to the old weight equals the ratio of the corresponding gravitational accelerations.


Step-by-Step Solution:

Let W_A = m * g1 at A.Let W_B = m * g2 at B.The multiplication factor when moving A → B is W_B / W_A = (m * g2) / (m * g1) = g2 / g1.


Verification / Alternative check:

If g2 = g1 there is no change and g2 / g1 = 1, which is consistent. If g2 is smaller (higher altitude), the factor is less than 1, indicating reduced weight—again consistent with experience.


Why Other Options Are Wrong:

  • g1 / g2 reverses the change direction.
  • (g1 + g2) / 2 is an average, not a scaling factor for weight change.
  • (g2 - g1) / g1 gives a fractional change, not the required multiplier.
  • 'Independent of location' contradicts the definition W = m * g.


Common Pitfalls:

  • Confusing mass (constant) with weight (varies with g).


Final Answer:

g2 / g1

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