Physics for IGCSE & O level - Forces And Motion (Section 9 - No. 6)
Which of the following will increase the friction between two surfaces?
Increasing the weight or the downward force on the object.
Reducing the surface area in contact.
Using rougher materials.
Polishing the surfaces to make them smooth.
Vysvetlenie
Rougher surfaces and a greater force pressing the surfaces together increases friction.