Answer:
f = 400 / 5 s = 80/sec frequency of revolution
P = 1/f = 1/(80/sec) = .0125 sec period of revolution
Probably to be more accurate. With hand-operated stop watches there is more room for (human) error.
Answer:
A) F_g = 4.05 10⁻⁴⁷ N, B) F_e = 9.2 10⁻⁸N, C)
= 2.3 10³⁹
Explanation:
A) It is asked to find the force of attraction due to the masses of the particles
Let's use the law of universal attraction
F = 
let's calculate
F = 
F_g = 4.05 10⁻⁴⁷ N
B) in this part it is asked to calculate the electric force
Let's use Coulomb's law
F = 
let's calculate
F = 
F_e = 9.2 10⁻⁸N
C) It is asked to find the relationship between these forces

= 2.3 10³⁹
therefore the electric force is much greater than the gravitational force
Answer:
B
Explanation:
Spectroscopy measures electromagnetic radiation.