To find the net force acting on the roller coaster, we can use Newton's second law of motion, which states that \( F = ma \), where:
- \( F \) is the net force,
- \( m \) is the mass,
- \( a \) is the acceleration.
Given:
- Mass \( m = 2000 \) kg,
- Acceleration \( a = 2 \) m/s².
Now, we can calculate the net force:
\[ F = ma = 2000 , \text{kg} \times 2 , \text{m/s}² = 4000 , \text{N} \]
So, the net force acting on the roller coaster is \( 4000 , \text{N} \).
The answer is D: 4000 N.