What would be an ideal experiment to test how different types of surfaces affect friction?

A)
Two objects of equal weight placed on two glass surfaces of equal lengths.

B)
Two objects of equal weight placed on two glass surfaces of unequal lengths.

C)
Two objects of equal weights placed on a glass surface and a wooden surface.

D)
Two objects of different weights placed on two wooden surfaces of unequal lengths.

Question

What would be an ideal experiment to test how different types of surfaces affect friction? 


 








  
A)
  Two objects of equal weight placed on two glass surfaces of equal lengths.   

 
  
B)
  Two objects of equal weight placed on two glass surfaces of unequal lengths.   

 
  
C)
  Two objects of equal weights placed on a glass surface and a wooden surface.   

 
  
D)
  Two objects of different weights placed on two wooden surfaces of unequal lengths.

anonymous · Answer

Any time you are doing an experiment and you want to check for an effect in particular, you must do your best to make sure that the ONLY thing that changes between runs of the experiment is the property you are interested in.  If too many things are all changing at the same time, it will be VERY hard to figure out which change caused what.  Does that make sense?

Knowing this, the answer should be obvious :)

anonymous · Answer

C.  :)