The time it takes "to complete one cycle" is a perfect definition for <em>period</em>.
So the <em>2 sec</em> that you measured is the swing's period.
Frequency is just 1/period (the 'reciprocal' of the period).
For this swing, the frequency is 1/(2sec) = 0.5 per second = <em>0.5 Hz</em>.
( "Hertz" means "per second")
Given:
The force of attraction is F = 48.1 N
The separation between the charges is

Also, the magnitude of charge q1 = q2 = q.
To find the magnitude of charge.
Explanation:
The magnitude of charge can be calculated by the formula

Here, k is the Coulomb's constant whose value is

On substituting the values, the magnitude of charge will be

Thus, the magnitude of each charge is 9.91 x 10^(-4) micro Coulombs.
Using Kepler's third law which is defined as the square of the average distance is directly proportional to the cube of the period. It is expressed as P^2 = a^3, Given that the a = average distance is given, the period would be much easier to compute. P = sqrt(27^3) = 140
Answer:
60.4 J
Explanation:
The work done by the gas is given by:

where
p is the gas pressure
is the final volume of the gas
is the initial volume
We must convert all the quantities into SI units:



So the work done is

The basic relationship between frequency of an electromagnetic wave and wavelength of the wave is

where

is the speed of light.
Manipulating the equation, we can rewrite it as

The frequency of the wave in our problem is

so if we use the previous formula, we find the correspondant wavelength: