At a given point above Earth's surface, the free-fall acceleration is equal to What is the altitude of this point above Earth's surface? (G = 6.67 10-11 N m2/kg2, Mearth = 5.97 1024 kg, Rearth = 6.38 106 m)
A) 770 km
B) 970 km
C) 1500 km
D) 2000 km
E) 2400 km
Question 2
If the distance between two charged objects and the charge on each of them are all doubled, the electric force by either one on the other is
A) reduced to one-quarter of the original force.
B) doubled.
C) quadrupled.
D) halved.
E) unchanged.