Question

Work done=?

• A. Force $\times$ Distance
• B. Mass $\times$ Velocity
• C. Power $\times$ Time
• D. Force $\times$ Acceleration

Hint:

Always remember: No movement = No work. You can push against a brick wall all day and feel tired, but in the eyes of physics, if the wall didn't move any distance, you did zero Joules of work.

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks for the fundamental formula that defines the concept of "Work" in classical physics.
Step 2: Key Formula or Approach:
The physics formula for work is more completely expressed as:
\[ W = F \cdot d \cdot \cos(\theta) \]
Here, \( F \) is the magnitude of the force, \( d \) is the magnitude of the displacement (distance), and \( \theta \) is the angle between the force vector and the displacement vector.
Step 3: Detailed Explanation:

• Core Definition: In physics, "work" is performed on an object only when an applied force causes it to move through a distance. If the object does not move, no work is done in the physical sense, no matter how great the force.
  
• Standard Case: For many simple problems, the force is applied in the same direction as the object's motion. In this case, the angle \( \theta \) is $0^{\circ}$, and since \( \cos(0^{\circ}) = 1 \), the formula simplifies to \( \text{Work} = \text{Force} \times \text{Distance} \). This is the relationship presented in option (A).
  
• Evaluating Alternatives:
  - Mass $\times$ Velocity (B): This is the formula for linear momentum (\( p = mv \)).
  - Power $\times$ Time (C): This calculation also equals work (\( W = P \times t \)), as power is the rate of doing work. However, Force $\times$ Distance is the more primary definition of work itself.
  - Force $\times$ Acceleration (D): This product does not correspond to a standard physical quantity. (Force is equal to mass $\times$ acceleration).
  
• Units of Work: The SI unit for work is the Joule (J). One Joule is defined as the work done by a force of one Newton acting over a distance of one meter.
  

Step 4: Final Answer:
The most fundamental definition of work provided among the choices is the product of Force and Distance.