Final answer:
In physics, the force exerted on the car when a motorist pulls on a rope is equal to the tension in the rope. Since the rope transmits equal and opposite forces at each end by virtue of being perfectly flexible and massless, the force exerted on the car is 200.0 N.
Step-by-step explanation:
To answer the question of determining the force exerted on the car when a motorist pulls sideways on the midpoint of a rope tied between a tree and the car, we must understand the concept of tension in physics. Tension is the force transmitted through a string, rope, cable or wire when it is pulled tight by forces acting from opposite ends.
According to the problem description and associated physics principles, if a motorist pulls with a force of 200.0 N at the midpoint of a 3.0-m rope, the rope will exert a force on the car that is equal to the tension in the rope.
Since the rope is presumed to be massless and perfectly flexible, the tension throughout the rope is constant, and Newton's third law tells us that the rope exerts equal but opposite forces on the tree and car.
The tension in the rope can be calculated using the formula for the tension in a rope under such conditions, which derives from the components of the applied force and the geometry of the situation.
However, typically, additional information such as the angle created by the displacement of the rope is used to find the exact magnitude of the tension.
Since the problem as presented does not provide an angle or a specific formula and implies that the force exerted by the person is directly transmitted to the car, we can imply that the force exerted on the car is also 200.0 N.