Final answer:
To achieve a net force of 386N due south on a crate with a 400N force acting due north, a force of 786N must be exerted due south.
Step-by-step explanation:
Understanding Net Force Calculation
A student has asked about determining an unknown force acting on a crate given a specific net force and a known force acting on it. In this particular situation, we have a 400N force acting due north on the crate, and we are looking for the force that must act due south if the net force is 386N due south.
To find this, we can use the principle of superposition of forces, where the net force is the vector sum of all the individual forces acting on an object. Assuming all the forces are in one dimension (north-south), the calculation is simplified to a subtraction of the northward force from the southward force.
If the net force on the crate is 386N due south, and there's already a 400N force acting north, we can set up the equation: unknown southward force - 400N = -386N (we take negative since the south is the opposite direction of north). Solving this equation gives us the unknown southward force = 400N - (-386N) = 786N. Therefore, a force of 786N due south must be exerted on the crate to achieve the net force of 386N due south.