The answer is 22.5 lb/gal.
The density of a liquid is quotient of mass and volume: D = m/V. The unit of the density is pound per gallon (lb/gal)
The density is unknown: D=?
But, we have:
mass: m= 90 lbs
volume: V = 4 gals
Do, the density of a liquid is:
D = 90 lbs / 4 gals
D = 22.5 lb/gal
Answer: 200metres per second
Explanation:
The wavespeed of a wave is the distance covered by the wave in one second. It is measured in metre per second, and represented by the symbol V.
Recall that Velocity (V) = Frequency F x wavelength λ
V = F λ
In this case, wavelength (λ)= 20 m frequency = 10 Hz.
Hence, V = F λ
= 20 metres x 10 hertz
= 200 metres per second
Thus, the wave travels at a speed of 200 metres per second
Answer:
Theory
Explanation:
A scientific theory is what best fits your description. A scientific theory basically explains aspects of the natural world. However, scientific theories are not just ideas, it is based on collaborative works that tests the idea through the scientific method. Theories are verified through repeated testing.
Scientific hypotheses can eventually become a scientific theory when results have been verified through repeated testing.
Materials that cannot be broken down by biological processes are known as non- biodegradable materials.
Such materials cannot be changed to a harmless natural state by action of bacteria. in other words, non biodegradable materials do not decay and are considered harmful to the environment.
Examples of non biodegradable materials include plastic products, electronic , construction waste. Common non biodegradable waste materials include plastic water bottles, tin cans, tires and computers. Such materials are discarded into landfills in an indiscriminate way, posing a major risk to the environment.
The answer is C. Cenozoic era.
It's the era when mammals evolved into larger organisms and began subdividing into various species. Cenozoic is also known as the age of mammals, because it's the mammals that mostly occupied the lands.