Olympiad Physics: Explaining the Correct Answer

[faiziqb12]

A problem came in the previous years Olympiad ::

if we go inside a mine and drop 10 lb iron ball and 1 lb allumunium ball from top of a high platform, then
1. both will reach the ground at same time
2. 1 lb weight will reach the floor first
3. 10 lb weight will reach the floor first
4. incomplete data

the answer is 1

but due to air resistance 10lb must have had fallen first..

please reason the correct answer

 

[Borg]

The difference in air resistance between the two spheres is neglible.

 

[faiziqb12]

but accordi

The difference in air resistance between the two spheres is neglible.

but force of friction must vary with diffrent mass
won't it

 

[Borg]

but accordi
but force of friction must vary with diffrent mass
won't it

Air resistance is dependent on surface area. Again, the difference is going to be negilible.

 

[faiziqb12]

Air resistance is dependent on surface area. Again, the difference is going to be negilible.

then can you please answer why a sheet of paper and a lead sheet of the same surface area experience different air resistance forces

please reply ASAP

 

[gneill]

then can you please answer why a sheet of paper and a lead sheet of the same surface area experience different air resistance forces

please reply ASAP

We won't do your work for you. You need to make some investigative effort here.

Choose representative masses for two objects. Assume that air resistance is identical for each, maybe call it f_air. Draw Free Body Diagrams for both. Determine expressions for the accelerations. How do the accelerations compare?