JAMB Physics 2010 Paper

Concept:Ignoring air resistance, all objects fall with the same acceleration due to gravity, regardless of their mass.Explanation:The gravitational force acting on an object is $F = mg$, where $m$ is the mass and $g$ is the acceleration due to gravity.From Newton's second law, the same force gives $F = ma$.Equating both expressions yields $ma = mg$, which simplifies to $a = g$.The mass $m$ cancels out, proving that the acceleration of free fall is independent of mass.A stone and a feather dropped from the same height therefore both experience the same acceleration $g = 9.8 \, \mathrm{m/s^2}$.Since air resistance is ignored and both start from rest, no other force slows either object down.Both objects travel the same vertical distance under the same uniform acceleration.Hence, the time taken to reach the ground is exactly the same for both objects.Answer:B. the stone and the feather will both reach the ground at the same time.