Friction can be increased or decreased depending on surface roughness. Increasing roughness with materials like rubber, leather, and spikes increases friction, while smoother surfaces like plastic and silk decrease friction. Lubricants are also used to reduce friction between moving machine parts to improve efficiency.

1. Increasing and Reducing
Friction

2. Replacing smooth surfaces with
rough ones can increase friction.
Materials like rubber, leather, and spikes
slows down motion.
Example:
– carpet
– rubber mat
– rubber shoes
– leather gloves

3. To decrease friction, one method is to
reduce the roughness of surfaces. using
smooth materials such as plastic cover or silk
cloth can make objects move fast and swift.
Examples:
– plastic cover
– silk cloth
– ball bearings or rollers

4. For machines, friction affects their
efficiency.
Lubricants are substances that are
applied to surfaces to reduce friction
between moving parts.
Examples:
– motor oil
– grease
– wax