Person sitting in a moving car is at rest with respect to:

1. A tree on the ground:
The person sitting in a moving car is not at rest with respect to a tree on the ground. From the perspective of the person in the car, the tree appears to be moving in the opposite direction with the same speed as the car. This is because both the car and the tree are in motion relative to the observer. Therefore, the person in the car is not at rest with respect to the tree on the ground.

2. A cyclist on the road:
Similar to the previous scenario, the person sitting in a moving car is not at rest with respect to a cyclist on the road. The cyclist, like the tree, appears to be moving in the opposite direction with the same speed as the car. This is because both the car and the cyclist are in motion relative to the observer. Hence, the person in the car is not at rest with respect to the cyclist on the road.

3. A building on the roadside:
Contrary to the previous cases, the person sitting in a moving car can be considered at rest with respect to a building on the roadside. This is because the building is stationary relative to the observer in the car. Even though the car and the observer are in motion, their relative motion to the building is negligible. Therefore, the person in the car can be considered at rest with respect to the building on the roadside.

4. The car:
The person sitting in a moving car is at rest with respect to the car itself. This is because both the person and the car are in the same frame of reference and share the same velocity. From the perspective of the person in the car, they are stationary with respect to the car. This is similar to how a person can be at rest when sitting inside a stationary room. Therefore, the person in the car is at rest with respect to the car.

In summary, the person sitting in a moving car is at rest with respect to the car itself and a building on the roadside. However, they are not at rest with respect to a tree on the ground or a cyclist on the road. The concept of rest is relative and depends on the frame of reference chosen.

The car