Question

increasing and decreasing friction
for each scenario listed below, decide whether it would increase or decrease friction, and
place a check mark in the appropriate box. then, if necessary, do some independent
research to determine how the action affects the friction between the surfaces involved.
the first one has been done for you as an example.
putting tread
patterns on tires
this gives water a place to squeeze
into on wet roads, allowing the tire
to make direct contact with the
road, thus increasing friction.
using adhesives
using lubrication
between two
surfaces
increasing the
mass of the object
polishing a wooden
floor
coating a pan with
teflon
putting rubber
soles on shoes

Explanation:

• Using adhesives: Adhesives create a strong bond between surfaces, which makes it harder for them to slide past each other. This increases the frictional force as there is more resistance to relative motion.
• Using lubrication between two surfaces: Lubricants like oil or grease fill the microscopic gaps and irregularities between surfaces. They form a thin layer that separates the surfaces, reducing the inter - molecular forces and the contact area. As a result, the frictional force is decreased.
• Increasing the mass of the object: According to the formula for frictional force \(F_f=\mu F_N\) (where \(\mu\) is the coefficient of friction and \(F_N\) is the normal force). When the mass \(m\) of an object is increased, the normal force \(F_N = mg\) (where \(g\) is the acceleration due to gravity) also increases. Since \(\mu\) (for a given pair of surfaces) remains constant, the frictional force \(F_f\) increases.
• Polishing a wooden floor: Polishing makes the surface smoother. A smoother surface has fewer irregularities. When two surfaces are in contact, the inter - locking of irregularities (a major contributor to friction) is reduced. So, polishing a wooden floor decreases friction.
• Coating a pan with Teflon: Teflon has a very low coefficient of friction. When a pan is coated with Teflon, the surface in contact with other substances (like food) becomes much less “sticky” or resistant to sliding. This is because the molecular structure of Teflon does not interact strongly with other materials, reducing the frictional force.
• Putting rubber soles on shoes: Rubber has a relatively high coefficient of friction. When rubber soles come in contact with surfaces (like the ground), the irregularities in the rubber can inter - lock well with the surface irregularities (of the ground, for example). This inter - locking provides more resistance to sliding, increasing the frictional force.

Answer:

Scenario	Increases Friction	Decreases Friction	Description
Using lubrication between two surfaces		✓	Lubricants separate surfaces, reducing inter - molecular and contact - based resistance (friction).
Increasing the mass of the object	✓		As \(F_f=\mu F_N\) and \(F_N = mg\), increasing \(m\) (mass) increases \(F_N\) (normal force) and thus \(F_f\) (friction) for constant \(\mu\).
Polishing a wooden floor		✓	Smoother surface reduces inter - locking of irregularities, decreasing friction.
Coating a pan with Teflon		✓	Teflon has a low coefficient of friction, reducing resistance to sliding.
Putting rubber soles on shoes	✓		Rubber’s high coefficient of friction and inter - locking with surfaces increases friction.