In the SI system, the unit of P.E. is

Options

A. erg
B. dyne-cm
C. J
D. none of lhese

Answer

To determine the SI unit of potential energy (P.E.), we can follow these steps:

### Step 1: Understand the Concept of Potential Energy
Potential energy is the energy possessed by an object due to its position or configuration. It is commonly associated with the height of an object in a gravitational field.

### Step 2: Recall the Formula for Potential Energy
The formula for gravitational potential energy is given by:
\[ PE = mgh \]
where:
- \( PE \) = potential energy,
- \( m \) = mass of the object (in kilograms),
- \( g \) = acceleration due to gravity (in meters per second squared),
- \( h \) = height above a reference point (in meters).

### Step 3: Determine the Units Involved
In the formula \( PE = mgh \):
- The unit of mass \( m \) in SI is kilograms (kg).
- The unit of gravitational acceleration \( g \) is meters per second squared (m/s²).
- The unit of height \( h \) is meters (m).

### Step 4: Calculate the Unit of Potential Energy
Now, substituting the units into the formula:
\[ \text{Unit of } PE = \text{kg} \cdot \left(\frac{\text{m}}{\text{s}^2}\right) \cdot \text{m} \]
This simplifies to:
\[ \text{Unit of } PE = \text{kg} \cdot \text{m}^2/\text{s}^2 \]
This unit is defined as a Joule (J).

### Step 5: Conclusion
Thus, the SI unit of potential energy is:
\[ \text{Joule (J)} \]

### Final Answer
The SI unit of potential energy is **Joule**.

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