Question

Given below are examples of friction shown in List-I with their respective types of friction in List-II.
List-I: (a) Pushing a chair, (b) Sea waves, (c) Moving heavy stationary objects, (d) Skating
List-II: (i) Sliding, (ii) Rolling, (iii) Fluid, (iv) Static

• A. (a)-(i), (b)-(iii), (c)-(ii), (d)-(iv)
• B. (a)-(iv), (b)-(ii), (c)-(i), (d)-(iii)
• C. (a)-(i), (b)-(iii), (c)-(iv), (d)-(ii)
• D. (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)

Hint:

Static friction is always the strongest type of friction, while rolling friction is the weakest. This is why it's harder to start moving a heavy box than to keep it sliding.

Answer 1

The Correct Option is C

To match the examples of friction in List-I with their respective types of friction in List-II, let's analyze each scenario step-by-step:

1. Pushing a chair: When you push a chair across the floor, it slides against the floor. This involves sliding friction, which occurs when two surfaces slide against each other. Hence, the correct match is (a)-(i).
2. Sea waves: Sea waves move through the water and air, which are fluids. This involves fluid friction, which occurs when objects move through a liquid or gas. Therefore, the correct match is (b)-(iii).
3. Moving heavy stationary objects: Initially, to start moving a heavy stationary object, you need to overcome the friction preventing motion, which is known as static friction. Hence, the correct match is (c)-(iv).
4. Skating: When you skate, the wheels of the skate roll on the surface, involving rolling friction. Therefore, the correct match is (d)-(ii).

Based on the analysis, the correct option is:

• (a)-(i)
• (b)-(iii)
• (c)-(iv)
• (d)-(ii)

Therefore, the correct answer is: (a)-(i), (b)-(iii), (c)-(iv), (d)-(ii).

Answer 2

A useful way to solve this kind of matching question is to start from the friction types in List-II, define what triggers each one, then see which List-I scenario fits.

1. Static friction (iv): This is the resistance that must be overcome before an object at rest starts to move. Moving a heavy stationary object requires exactly this, so pushing a heavy stationary object matches static friction.
2. Sliding friction (i): This acts once two solid surfaces are already moving relative to each other, rubbing directly. Pushing a chair makes its legs drag along the floor while in contact with it, a classic sliding scenario, so pushing a chair matches sliding friction.
3. Rolling friction (ii): This occurs when a round or wheeled object rolls over a surface instead of sliding across it. Skating involves wheels or blades rolling along the rink or floor, so skating matches rolling friction.
4. Fluid friction (iii): This is the drag experienced by an object moving through a liquid or gas. Sea waves are water moving through and against itself and the surrounding air, a fluid medium interaction, so sea waves match fluid friction.

Working from the type definitions gives the same four pairings: pushing a chair with sliding, sea waves with fluid, moving heavy objects with static, and skating with rolling.

Therefore, the correct answer is (a)-(i), (b)-(iii), (c)-(iv), (d)-(ii).