Technological advances clearly.
Theories change due to other peoples view on the matter and how they experiment with it, but Technology advancements are the greatest factor of all. I mean seriously, we wouldn't know of cells before the microscope and when they first invented it, it advanced further and now we can see things on a whole deeper lever.
Answer:
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Explanation:
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Friction occurs when the surfaces and heat of two surfaces grind against each other.
I think these are the answers
When she starts out, he is (40x2.5)= 100 miles ahead of her.
She gains (65-40)= 25 miles on him every hour.
It takes her (100/25)= 4 hours to catch up to him.