# Why doesn't air below a falling object balance its weight? [duplicate]

Consider the following scenario: a body is dropped and it hits the air molecules below it with a force equal to it's weight. By Newton's third law, the air molecules below should exert the same force on the body and force due to weight should cancel out and object should not fall. Why doesn't this happen?

## marked as duplicate by Martin, ACuriousMind♦, bobie, JamalS, Kyle KanosJan 19 '15 at 13:33

• Think about the mass of the respective objects and the resultant acceleration – Chris2807 Jan 19 '15 at 12:27
• This is a duplicate of many questions already in here such as: physics.stackexchange.com/questions/39215/… or physics.stackexchange.com/questions/45653/… – Martin Jan 19 '15 at 12:29
• This is not a duplicate to the marked question. The OP's misunderstanding is not Newton's 3rd law - he's correct that the air molecules and the body put equal and opposite forces on each other - his mistake is thinking that when a falling body hits an air molecule, that force must be the same as the body's weight. It's a misunderstanding of the force objects put on each other when they have a collision. – Brionius Jan 19 '15 at 20:29
• @Brionius Can you please elaborate further? – Apoorv Jan 20 '15 at 20:21
• When the object hits an air molecule, it does not put a force equal to its weight on the air molecule. The force that one object puts on another in a collision is determined by relative speed, impact angle, and the characteristics of the objects' surfaces. It's determined by conservation of energy, and the energy lost due to inelasticity of the objects. – Brionius Jan 20 '15 at 20:30