Answer:
Based on the given information, the best scale to represent the magnitude of the weight of car 9000N on a diagram is 1cm:1000N.
Step-by-step explanation:
To represent the magnitude of the weight of a car of 9000N, the best scale would be 1 cm:1000N, since 1 cm:100N would result in a diagram that is too large, and 1 cm:10000N would result in a diagram that is too small. With the scale of 1 cm:1000N, the weight of the car can be represented by a line segment of 9 cm, which is a reasonable size for a diagram.