If we imagine two ideally smooth surfaces & if they are kept in contact, the frictional force acting between them is,

Options

A. zero
B. a small finite value but not zero
C. very high
D. we can't predict

Answer

To solve the problem, we need to determine the frictional force acting between two ideally smooth surfaces that are in contact. Here’s a step-by-step breakdown of the solution:

### Step 1: Understand the Concept of Friction
Friction is a force that opposes the relative motion of two surfaces in contact. The frictional force (f) can be calculated using the formula:
\[ f = \mu \cdot N \]
where:
- \( \mu \) is the coefficient of friction between the two surfaces,
- \( N \) is the normal force acting perpendicular to the surfaces.

### Step 2: Identify the Coefficient of Friction
For ideally smooth surfaces, the coefficient of friction (\( \mu \)) is considered to be zero. This is because ideally smooth surfaces do not have any roughness or irregularities that would allow for friction to occur.

### Step 3: Apply the Formula
Since we have established that \( \mu = 0 \) for ideally smooth surfaces, we can substitute this value into the friction formula:
\[ f = 0 \cdot N \]
This simplifies to:
\[ f = 0 \]

### Step 4: Conclusion
Thus, the frictional force acting between two ideally smooth surfaces in contact is zero.

### Final Answer
The frictional force acting between two ideally smooth surfaces kept in contact is **zero**.

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