Capacity to do work is :

Question

Accepted Answer

The correct answer to the question "Capacity to do work is:" is Option 3, Energy.

1. **Explanation for Option 3 (Energy):**
   - Energy is defined as the capacity to do work. In physics, work is done when a force is applied to an object and the object moves in the direction of the force. Energy is what enables this process to occur. It exists in various forms, such as kinetic energy, potential energy, thermal energy, and more. Without energy, no work can be performed, as it is the fundamental requirement for any physical activity or process.

2. **Explanation for why the other options are incorrect:**

- **Option 1 (Force):**
     - Force is a vector quantity that refers to an interaction that, when unopposed, will change the motion of an object. While force is necessary to perform work, it is not the capacity to do work itself. Instead, force is one of the components required to perform work, with energy being the underlying capacity that allows force to be applied.

- **Option 2 (Power):**
     - Power is the rate at which work is done or energy is transferred over time. It is measured in watts in the International System of Units (SI). While power is related to work and energy, it specifically describes how quickly work is done, not the capacity to do work itself. Therefore, power is not the correct answer to the question.

- **Option 4 (Friction):**
     - Friction is a force that opposes the relative motion or tendency of such motion of two surfaces in contact. It is not related to the capacity to do work; rather, it often acts as a resistance that needs to be overcome to perform work. Friction can convert kinetic energy into thermal energy, but it does not represent the capacity to do work.

In conclusion, energy is the correct answer because it is the fundamental concept that represents the capacity to perform work, making Option 3 the appropriate choice.