Final answer:
The acceleration of a car with two washers on a string is affected by the car's mass, surface friction, and the string's tension, as per Newton's second law of motion.
Step-by-step explanation:
The acceleration of the car with two washers on the string can be influenced by several factors including the mass of the car, friction on the surface, and tension in the string. According to Newton's second law, the net force acting on an object is equal to the mass of the object multiplied by its acceleration. If we consider a setup where a string is attached to the car and two washers, with the string passing over a pulley, the tension in the string is related to the weight of the washers. The friction between the car and the surface it moves on will resist the car's movement and thus affect the acceleration as well. Therefore, to determine the acceleration, you'll need to consider all these factors.