Answer:
Re = 1 10⁴
Explanation:
Reynolds number is
Re = ρ v D /μ
The units of each term are
ρ = [kg / m³]
v = [m / s]
D = [m]
μ = [Pa s]
The pressure
Pa = [N / m²] = [Kg m / s²] 1 / [m²] = [kg / m s²]
μ = [Pa s] = [kg / m s²] [s] = [kg / m s]
We substitute the units in the equation
Re = [kg / m³] [m / s] [m] / [kg / m s]
Re = [kg / m s] / [m s / kg]
RE = [ ]
Reynolds number is a scalar
Let's evaluate for the given point
Where the data for methane are:
viscosity μ = 11.2 10⁻⁶ Pa s
the density ρ = 0.656 kg / m³
D = 2 in (2.54 10⁻² m / 1 in) = 5.08 10⁻² m
Re = 0.656 4 2 5.08 10⁻² /11.2 10⁻⁶
Re = 1.19 10⁴
Choices 'C' and 'D' are both correct.
(Except in 'C', changing the temperature from 1°C to 3°C is not usually
described as 'cooling', and it's not the water's 'mass' that changes. But
water does contract in volume during that change.)
Answer:
The only parameter that changes is mass m
It is only necessary to calculate the ratio Eh/Ee
The kinetic energy of the heavy paricle is three times the kinetic energy of an electron
It has to be one continuous column of cloud (air) connected to the ground and in constant rotation.
Answer:
8.5 Ω
Explanation:
La resistencia de un material es directamente proporcional a su longitud e inversamente proporcional al área de la sección transversal.
La fórmula de la resistencia (R) viene dada por:
R = ρL/A
Donde ρ es la resistividad del material, L es la longitud del material y A es el área de la sección transversal del material.
Dado que:
L = 1 km = 1000 m, A = 2 mm² = 2 * 10⁻⁶ m², ρ (cobre) = 1.7 * 10⁻⁸ Ωm
Sustituyendo da:
R = 1,7 * 10⁻⁸ * 1000/2 * 10⁻⁶
R = 8.5 Ω
