The ability of singers to shatter glass is due to the control of frequency in their voices. The sound waves will vibrate the air particles that surround the glass at its resonant frequency. The glass will break if a singer sings too loudly.
The answer is B) wavelength
To solve this problem we will apply the concepts related to energy conservation. Here we will understand that the potential energy accumulated on the object is equal to the work it has. Therefore the relationship that will allow us to calculate the height will be


Here,
m = mass
g = Acceleration due to gravity
h = Height
our values are,



Replacing,



Then the height is 32.83m.
Answer: A. 200J
Therefore, the workdone by the heat engine is 200J
Explanation:
Given ;
The efficiency of the heat engine is E = 20% = 0.2
Heat loss L= 800J
For an heat engine the efficiency is measured by the amount of workdone by the heat engine when compared to the heat generated.
Efficiency E = workdone/heat generated × 100%
Heat generated G= workdone W + heat loss L
G = W + L
According to the question.
W = 20% of G
W = 0.2G ......1
L = 80% of G
L = 0.8G
G = L/0.8 ......2
Substituting equation 2 to 1
W = 0.2(L/0.8)
And L = 800J
W = 0.2(800/0.8)
W = 200J
Therefore, the workdone by the heat engine is 200J