The law of universal gravitation is written F = GMm/r2. Why did we use the form F = mg when we studied projectile motion?

A. The first form is not valid for projectile motion.
B. The first form does not work because it requires two masses.
C. The first form is not valid near the surface of Earth.
D. The second form is a good approximation to the first and much simpler to use.


Answer: D. The second form is a good approximation to the first and much simpler to use.

Physics & Space Science

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