To solve the problem it is necessary to use the concepts related to the calculation of periods by means of a spring constant.
We know that by Hooke's law

Where,
k = Spring constant
x = Displacement
Re-arrange to find k,




Perioricity in an elastic body is defined by

Where,
m = Mass
k = Spring constant


Therefore the period of the oscillations is 0.685s
Answer:
The object on earth, because earth has a bigger amount of gravity than how much the moon has.
Explanation:
Answer:
Magnetic activity and sunspots are in a proportional relationship.
Explanation:
From the graph, as one increases, so does the other, thus we describe the relationship as proportional.
Other than that, all of your other answers seem correct.
Answer:
10.0 zero, by Gauss' Law the symmetrical distribution will produce no internal electric fields
21.5 E = k Q / R^2 behaves as if all charge were at center
E = 9 E9 * 29.5 E-6 / .215^2 = 5.74E6 N/C
Answer:

Explanation:
As we know that the oil drop experiment tells us the balancing the gravitational force by electrostatic force.
So ,
Electrostatic force = Gravitational force
qE=mg
Here , q is charge , E is electric field , m is mass and g is gravity.
so,

Insert values from question,

or

This is the required value of electric field.