The properties that change how we perceive light waves are the following:
The amplitude of the light wave changes the brightness of light relative to other light waves of the same wavelenghth.
The frequency of the light wave changes the color and the type of the light wave.
Answer:
1/2 Hz
Explanation:
A simple harmonic motion has an equation in the form of

where A is the amplitude,
is the angular frequency and
is the initial phase.
Since our body has an equation of x = 5cos(π t + π/3) we can equate
and solve for frequency f

f = 1/2 Hz
Answer:
A & D
Explanation:
A single-displacement reaction is a chemical reaction whereby one element is substituted for another one in a compound and thereby generating a new element and also a new compound as products.
From the options, only options A & D fits this definition of single-displacement reactions.
For option D: Both left and hand and right hand sides each have one element and one compound. We can see that K is substituted from KBr to join Cl to form KCl and Br2 on the right hand side.
For option A: Both left and hand and right hand sides each have one element and one compound. We can see that OH is substituted from 2H2O to join Mg to form Mg(OH)2 and H2 on the right hand side.
The other options are not correct because they don't involve only and element and a compound on each side of the reaction.
We will have the following:

So, the heat to add is 3611.52 Joules.