2015 · Q42
Which one of the following statements is not correct?
General KnowledgePhysics
- AWeight of a body is different on different planets.
- BMass of a body on the earth, on the moon and in empty space is the same.
- CWeightlessness of a body occurs when the gravitational forces acting on it are counter-balanced.
- DWeight and mass of a body are equal at sea level on the surface of the earth.
Explanation
Weight (mass times g) differs across planets, mass is invariant, and weightlessness occurs in free fall or orbit where gravitational effects are counterbalanced — so A, B, and C are true. But weight is a force measured in newtons and mass is measured in kilograms; they are different quantities and are never equal, even at sea level where g is about 9.8 m/s2. Hence D is the incorrect statement.