Correct question is;
A thermal tap used in a certain apparatus consists of a silica rod which fits tightly inside an aluminium tube whose internal diameter is 8mm at 0°C.When the temperature is raised ,the fits is no longer exact. Calculate what change in temperature is necessary to produce a channel whose cross-sectional is equal to that of the tube of 1mm. (linear expansivity of silica = 8 × 10^(-6) /K and linear expansivity of aluminium = 26 × 10^(-6) /K).
Answer:
ΔT = 268.67K
Explanation:
We are given;
d1 = 8mm
d2 = 1mm
At standard temperature and pressure conditions, the temperature is 273K.
Thus; Initial temperature; T1 = 273K,
Using the combined gas law, we have;
P1×V1/T1 = P2×V2/T2
The pressure is constant and so P1 = P2. They will cancel out in the combined gas law to give:
V1/T1 = V2/T2
Now, volume of the tube is given by the formula;V = Area × height = Ah
Thus;
V1 = (πd1²/4)h
V2 = (π(d2)²/4)h
Thus;
(πd1²/4)h/T1 = (π(d2)²/4)h/T2
π, h and 4 will cancel out to give;
d1²/T1 = (d2)²/T2
T2 = ((d2)² × T1)/d1²
T2 = (1² × T1)/8²
T2 = 273/64
T2 = 4.23K
Therefore, Change in temperature is; ΔT = T2 - T1
ΔT = 273 - 4.23
ΔT = 268.67K
Thus, the temperature decreased to 268.67K
Probably for the umbilical cord that connects babies (from their early stages in the womb to their removal) to their mothers. The cord is cut, forming the belly button. This is analogous to astronauts in space.
30grams
Explanation:
If a reaction starts with 30grams then the reaction should end with 30grams.
This in conformity with the law of conservation of mass.
- The law states that "in an isolated system, mass is neither created nor destroyed during chemical transformation".
- Mass is the quantity of matter contained in a substance.
- In chemical reactions, the mass of reactants must always be the same with the mass of the product baring any loss.
- In an isolated system, there is no exchange of energy and mass.
- Chemical systems are usually treated as isolated systems in which mass is conserved.
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Answer:
42m/s
6.06s
Explanation:
To find the initial velocity and time in which the ball is fling over the ground you use the following formulas:

θ: angle = 45°
vo: initial velocity
g: gravitational constant = 9.8m/s^2
x_max: max distance = 180 m
t_max: max time
by replacing the values of the parameters and do vo the subject of the first formula you obtain:

with this value of vo you calculate the max time:

hence, the initial velocity of the ball is 42m/s and the time in which the ball is in the air is 6.06s
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TRANSLATION:
Para encontrar la velocidad inicial y el tiempo en el que la pelota está volando sobre el suelo, use las siguientes fórmulas:
θ: ángulo = 45 °
vo: velocidad inicial
g: constante gravitacional = 9.8m / s ^ 2
x_max: distancia máxima = 180 m
t_max: tiempo máximo
reemplazando los valores de los parámetros y haciendo el tema de la primera fórmula que obtiene:
con este valor de vo usted calcula el tiempo máximo:
por lo tanto, la velocidad inicial de la pelota es de 42 m / sy el tiempo en que la pelota está en el aire es de 6.06 s