A girl is pulling a sled up a hill with a force of 5N. The wind is blowing at her back (uphill) with a force of 15N. The force of gravitity is 20N and friction between her boots and the snow is 5N. What is the net force, including direction, of this situation?

To find the net force in this situation, we need to sum up all the forces acting on the sled and determine their direction.

Let's consider the forces acting on the sled:

1. The force applied by the girl pulling the sled uphill: 5N (opposite to the direction of motion)

2. The force of the wind blowing at her back (uphill): 15N (opposite to the direction of motion)

3. The force of gravity acting downward: 20N (opposite to the direction of motion)

4. The frictional force between her boots and the snow: 5N (opposite to the direction of motion)

To calculate the net force, we need to consider both the magnitude and direction of each force. Since forces can be either positive or negative depending on the direction, we can assign a negative sign to forces acting in the opposite direction of the motion.

Net force = Sum of all the forces

Net force = (-5N) + (-15N) + (-20N) + (-5N)

Net force = -45N

Therefore, the net force is -45N, indicating that the overall force is acting in the opposite direction of the motion (downhill in this case).