Answer:
a) P' = P_original, b) P ’= P_original + ρ g Δh
Explanation:
The expression for nanometric pressure is
P = ρ g h
where ρ is the density of the liquid and h is the height
a) we change the radius of the barrel, but keeping the same height
as the pressure does not depend on the radius it remains the same
P' = P_original
b) We change the barrel height
h ’≠ h
we substitute in the equation
P ’= ρ g h’
h ’= h + Δh
P ’= ρ g (h + Δh)
P ’= (ρ g h) + ρ g Δh
P ’= P_original + ΔP
In this case, the pressure changes due to the new height,
*if it is higher than the initial one, the pressure increases
*if the height is less than the initial one, the pressure is less
Answer:
Explanation:
In 1789, Antoine Lavoisier published a list of 33 chemical elements. Although Lavoisier grouped the elements into gases, metals, non-metals, and earths, chemists spent the following century searching for a more precise classification scheme. In 1829, Johann Wolfgang Döbereiner observed that many of the elements could be grouped into triads (groups of three) based on their chemical properties. Lithium, sodium, and potassium, for example, were grouped together as being soft, reactive metals. Döbereiner also observed that, when arranged by atomic weight, the second member of each triad was roughly the average of the first and the third.[19] This became known as the Law of Triads.[20] German chemist Leopold Gmelin worked with this system, and by 1843 he had identified ten triads, three groups of four, and one group of five. Jean Baptiste Dumas published work in 1857 describing relationships between various groups of metals. Although various chemists were able to identify relationships between small groups of elements, they had yet to build one scheme that encompassed them all.[19]
