As we know that intensity of sound is defined as power received per unit area
so here the power of source is given as

distance of microphone is given as

now if loudspeaker is considered as spherical source then we will have


here
r = d = 60 m


Answer:
C. 45
Explanation:
Took the quiz and got it right
Answer:
How much energy does it take to melt a 16.87 g ice cube? ΔHfus = 6.02 kJ/mol How much energy does it take to melt a 16.87 g ice cube? = 6.02 kJ/mol
A. 108 kJ
B. 102 kJ
C. 5.64 kJ
D. 936 kJ
E. none of the above
<em>5.64 kJ</em>
Explanation:
The Heat of fusion is the heat energy required to dissolve a given mass of ice at melting point.
<h3>
Step by Step Calculation</h3>
The heat energy required to dissolve ice can be calculated using the expression below;
Q = ΔH
x m ...............................................1
where Q is the heat energy required;
ΔH
is the heat of fusion for ice;
m is the mole
All the parameters above are provided in the question except m, so to get m we use the molar mass of water (also for ice) which is 18.01528 g/mol
.
<em>This means that 18.01528 g of ice is contained in one mole, therefore the mole for 16.87 g of ice is given as;</em>

m = 0.9364 mole of ices
Now the parameters are complete, we are given;
ΔH
= 6.02 kJ/mol
m = 0.9364 mol
Q =?
Substituting into equation 1, we have
Q = 6.02 kJ/mol x 0.9364 mol
Q = 5.64 kJ
<em>Therefore, the energy required to melt 16.87 g of ice is 5.64 kJ</em>
This is best explained through the use of an optics diagram, this is a little too complicated to explain in a short answer, and as I can't draw an appropriate diagram in this answer, I will point you to this excellent resource which explains what you have asked very well!
Go onto the BBC website (you should have access to it even if you aren't in the UK) and paste this after the BBC url,
/bitesize/intermediate2/physics/waves_and_optics/image_formation_from_lens/revision/1/
Answer:
1.- para cubrir la superficie lateral 4.32 metros²
2.- Area de la base 2.15 metros²
3.- Volumen 1 m³
4.- Area total 6.47 metros²
Explanation:
El área lateral sera calcular el area de seis triangulos iguales cuya base es
0.80 de base x 6 lados = 4.80 metros perimetro de la base
4.80 perimetro de base x 1.80 arista lateral / 2 = 4.32m2
Area de la base:
Perímetro x Apotema / 2
Siendo la Apotema la altura de los triangulos que componen un hexagono calculada utilizando el teorema de pitágoras:

Apotema = 0.894427191
Area: 4.80 x 0.894427191 / 2 = 2.146625258
sumando el area de la base mas el area lateral se obtiene el area total
2.15 + 4.32 = 6.47 metros
Volumen de la pirámide:
Area de la Base x Altura / 3
2.15 x 1.40 / 3 = 1.00333 m3