Answer:
The thickness of the foil is 0.017 mm.
Explanation:
Given that,
Weight = 7.5 oz = 212.6175 gm
Density = 2.70 g/cm³
Area of aluminium = 50 ft² = 46451.52 cm²
We need to calculate the thickness of the foil
Using formula of density



Where, A = area
t = thickness
m = mass
Put the value into the formula



Hence, The thickness of the foil is 0.017 mm.
Answer: Vibrating
Explanation:
Sound is produced when an object vibrates. The sound vibrations cause waves of pressure that travel through a medium, such as air, water, wood or metal. Sound is a form of mechanical energy.
Explanation:
Two waves with the same wavelength are in phase if there phase difference is zero or an integral multiple of wavelength. Thus the integer part of any difference expressed in wavelength can be discarded.
The phase difference of 5.4 wavelength is equivalent to is one of 0.4 wavelength thus the interference is an intermediate interference close to fully destructive.
It's B because it talks about if it harms people. That would be an example of a medical/ethical issue.