Question

Which observation shows that interlocking of irregularities is not the real or primary cause of friction?

Options

• Friction disappears in liquids

• Friction is always zero on rough surfaces

• Making surfaces smoother sometimes increases friction

• Friction only acts on heavy objects

Answer 1

Making surfaces smoother sometimes increases friction

Explanation:

When surfaces are highly polished (very smooth), friction can increase, so interlocking cannot be the main cause.