**Correct Option: C. 0 N** ### Detailed Explanation: 1. **Understanding Forces**: - When we analyze the forces acting on an object, we need to identify all the forces and their directions. In this case, we have two forces acting on the 10 kg object: - **Weight (W)**: This is the force due to gravity acting downward. It can be calculated using the formula: \[ W = m \cdot g \] where \( m \) is the mass of the object (10 kg) and \( g \) is the acceleration due to gravity (approximately \( 9.81 \, \text{m/s}^2 \)). \[ W = 10 \, \text{kg} \cdot 9.81 \, \text{m/s}^2 = 98.1 \, \text{N} \] So, the weight of the object is approximately 98.1 N downward. - **Normal Force (N)**: This is the force exerted by the surface that supports the weight of the object. It acts upward and, in this case, balances the weight of the object when it is at rest. Therefore, the normal force is also 98.1 N upward. 2. **Net Force Calculation**: - The net force (\( F_{\text{net}} \)) acting on an object is the vector sum of all the forces acting on it. Since the object is at rest, we can set up the equation: \[ F_{\text{net}} = N - W \] - Substituting the values we calculated: \[ F_{\text{net}} = 98.1 \, \text{N} \, (\text{upward}) - 98.1 \, \text{N} \, (\text{downward}) = 0 \, \text{N} \] - Since the upward normal force exactly balances the downward weight, the net force is 0 N. 3. **Why Other Options Are Incorrect**: - **Option A: 10 N upward**: This option incorrectly suggests that there is a net force of 10 N acting upward. However, we calculated the normal force to be 98.1 N, which balances the weight of the object. Therefore, this option is incorrect. - **Option B: 10 N downward**: This option implies that there is a net force of 10 N acting downward. This is also incorrect because the weight of the object is 98.1 N downward, and it is balanced by the normal force. - **Option D: 20 N upward**: This option suggests a net force of 20 N acting upward, which is not supported by our calculations. The forces are balanced, resulting in a net force of 0 N, not 20 N. ### Summary: - The object is at rest, meaning the forces acting on it are balanced. - The weight of the object (98.1 N downward) is balanced by the normal force (98.1 N upward). - The net force acting on the object is 0 N, confirming that it is in equilibrium. ### Revision Summary: - The net force is the vector sum of all forces acting on an object. - For an object at rest on a horizontal surface, the normal force balances the weight. - If forces are balanced, the net force is zero. - Always check the direction of forces when calculating net force.