Answer: i can see properly
Explanation:
The added weight of the sand puts more downward pressure on the wheels contacting the rails, which would cause the trains speed to decrease.
Distance between the two cars is increasing at the rate of 85 mph.
A passenger in Car-1 says that he is at rest in his own frame of reference,
and Car-2 is moving away from him at 85 mph, toward the west.
I think frequency it sounds like the correct answer but I am not completely sure if I am correct
