Responses revealed that solid friction and viscosity topics are poorly treated in schools. Many candidates
had good ideas but could not assemble them together. Some candidates even mismatched points listed.

The expected answers are:

Differences between solid friction and viscosity

Solid friction	Viscosity
- Independent of surface area in contact	Depends on surface area in contact
Depends on normal reaction (of one solid surface on the other)	Independent of normal reaction
Occurs between solids surfaces in contact	Occurs between fluid layers/solid and fluid in contact/in fluids
Independent of relative velocity (between solid surfaces in contact)	Depends on relative velocity (between fluid layers)