Riley is doing an experiment working with friction. he wants to find two ways to modify an object that could increase or decrease the same type of friction. which methods could he use to perform his experiment?

1.increasing roughness and speed
2.increasing surface area and aerodynamic design
3.using nonstick materials and ball bearings
4.using lubricants and increasing surface area

2.increasing surface area and aerodynamic design

Explanation:

Air drag or air friction is the resistance force of air molecules which resist the motion of object while it is in motion.

Air draw on a moving object is given as

so from above formula we can say that it depends on

A = area of object

v = speed of object

= drag coefficient which depends on shape and size of object

So here we can say that correct answer will be

2.increasing surface area and aerodynamic design

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