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.
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What is the intensity of the light that has passed through both polarizers?
a. 
b. 
c. 
d. 
E. 0.00
What is the kinetic energy of a 0.135 kg baseball thrown at 40.0 m/s?
a. 54.0 J b. 87.0 J c. 108 J d. 216 J
The scientist credited with discovering that electric currents produce magnetic fields was
A. Tesla. B. Coulomb. C. Faraday. D. Oersted. E. Ampere.
The most disorderly arrangement of energy within matter is also
A) the least probable state of matter. B) the most probable state of matter. C) a matter of certainties, not probabilities. D) none of the above