If the downward force between surfaces is doubled, what happens to static friction?

When examining the relationship between static friction and the downward force exerted between two surfaces, it's essential to understand how static friction is calculated. Static friction is determined by the equation:

[ F_s = \mu_s \cdot N ]

where ( F_s ) is the static frictional force, ( \mu_s ) is the coefficient of static friction, and ( N ) is the normal (downward) force.

If the downward force (normal force) is doubled, the static frictional force will also double, assuming that the coefficient of static friction remains constant. This relationship indicates that static friction is directly proportional to the normal force. Therefore, if the normal force increases, static friction increases correspondingly.

The other choices reflect misunderstandings of the relationship between static friction and normal force. The notion of static friction increasing by the square root of the force does not align with the linear relationship established by the formula. Similarly, a decrease by half or remaining constant contradicts the direct proportionality that exists in this scenario. Thus, as the downward force is doubled, the static friction will indeed double as well.