Final answer:
The frictional force that acts on the crate is equal in magnitude and opposite in direction to the horizontal push you exert. Friction acts to prevent the crate from sliding or moving on the level floor. The applied force must be greater than the maximum static friction force for the crate to start moving.
Step-by-step explanation:
The frictional force that acts on the crate is equal in magnitude and opposite in direction to the horizontal push you exert. This is because the crate is at rest and there is no net external force acting on it. According to Newton's third law of motion, for every action, there is an equal and opposite reaction.
Friction acts to prevent the crate from sliding or moving on the level floor. In order for the crate to start moving, the applied force must be greater than the maximum static friction force between the crate and the floor.
For example, if you exert a force of 50 N on the crate and it doesn't move, the friction force acting on the crate will also be 50 N in the opposite direction.