Final answer:
On a frictionless surface, if the crate moves to the left, the net force is zero to the left, as per Newton's first law of motion, which states that an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
Step-by-step explanation:
If we assume the crate is on a frictionless surface and it moves to the left, the net force on the crate would also be to the left. This is because force is a vector, and vector addition tells us that the sum of forces (or the net force) will point in the direction of the crate's motion if no other forces oppose it. In a frictionless environment, if no other external forces are applied, the crate would continue to move to the left with a constant velocity, as per Newton's first law of motion, also known as the law of inertia. If the crate moves to the left without friction or any other opposing forces, the net force is zero left since no force is needed to maintain constant velocity in the absence of friction according to Newton's first law.