**Category:** Mechanics  
**Subtype:** Oscillations (Simple Harmonic Motion)  
**Problem Description:** This problem involves a spring pendulum (spring-mass system) oscillating vertically. We need to find the total mechanical energy of the system when the spring is compressed to a certain length and the velocity of the mass is zero.  

**Key Information:**
- Natural length of the spring: 20 cm
- Compressed length of the spring: 18 cm
- Mass of the object: 200 g (0.2 kg)
- Gravitational acceleration: g = 10 m/s²
- Spring force (restoring force) when compressed: 2 N

**What to Find:** The total energy of the oscillating mass-spring system.