Ask question

Ask question

All categories

3 years ago

8

If a 72-candela light source is located at a distance of 3 meters from a surface, the illuminance on the surface is _______ lux.

A. 648 B. 24 C. 8 D. 216

2 answers:

myrzilka [38]3 years ago

8 0

I took the test and the answer was C. 8

erastova [34]3 years ago

3 0

My friend told me it was C, 8 !

You might be interested in

instrucions classify the following reactions as synthesis, decomposition,single replacement, double replacement, or combustion.

My name is Ann [436]

Answer:

There are no specific equations but here what i can give you:

1. Synthesis -- A synthesis reaction is a chemical change in which two or more substances react to form a single new substance.

In all synthesis reactions, there is a single product that is a compound!

2. Decomposition -- A decomposition reaction is a chemical change in which a single compound breaks down into two or more simpler products. (This is the opposite of synthesis reactions!)

Most decomposition reactions require energy in the form of heat, light, and electricity.

3. Single Replacement -- A single-replacement reaction is a chemical change in which one element replaces a second element in a compound. You can identify a single-replacement reaction by noting that both the reactants and the products consist of an element and a compound.

4. Double Replacement -- A double-replacement reaction is a chemical change involving an exchange of positive ions between two compounds.

For a double replacement reactions to occur, one of the following is usually true:

- One of the products is only slightly soluble and precipitates from solutions.

- One of the products is a gas.

- One product is a molecular compound such as water.

5. Combustion -- A combustion reactions is a chemical change in which an element or a compound reacts with oxygen, often producing energy in the form of heat or light.

A combustion reactant always involves oxygen as a reactant. (If the supply of oxygen is limited, then the combustion will not be complete.)

The other reactant is a hydrocarbon, which is a compound composed of hydrogen and carbon and the complete combustion of a hydrocarbon produces CO2 and H2O.

Hydrocarbons include methane, propane, and butane.

I really hope this helps you!

3 0

3 years ago

Un móvil se mueve con movimiento acelerado. En los segundo 2 y 3 los espacios recorridos son 90 y 120 m, Calcula la velocidad in

faust18 [17]

Answer:

La velocidad inicial es 55 $\frac{m}{s}$ y su aceleración es -10 $\frac{m}{s^{2} }$

Explanation:

Un movimiento es rectilíneo uniformemente variado, cuando la trayectoria del móvil es una línea recta y su velocidad varia la misma cantidad en cada unidad de tiempo . Dicho de otra manera, este movimiento se caracteriza por una trayectoria que es una línea recta y la velocidad cambia su módulo de manera uniforme: aumenta o disminuye en la misma cantidad por cada unidad de tiempo. Y la aceleración es constante y no nula (diferente de cero).

En este caso la posición del objeto esta dada por la expresión:

$x=x0+v0*t+\frac{1}{2} *a*t^{2}$

donde x es la posición del cuerpo en un instante dado, x0 la posición en el instante inicial, v0 la velocidad inicial y a la aceleración.

En este caso, por un lado podes considerar:

x= 90 m
x0= 0 m
v0= ?
t= 2
a= ?

Reemplazando obtenes:

$90=v0*2+\frac{1}{2} *a*2^{2}$

$90=v0*2+\frac{1}{2} *a*4$

$90=v0*2+2*a$

Y por otro lado tenes:

x= 120 m
x0= 0
v0= ?
t= 3
a= ?

Reemplazando obtenes:

$120=v0*3+\frac{1}{2} *a*3^{2}$

$120=v0*3+\frac{1}{2} *a*9$

$120=v0*3+\frac{9}{2} *a$

Por lo que tenes el siguiente sistema de ecuaciones:

$\left \{ {{2*v0+2*a=90} \atop {3*v0+\frac{9}{2} *a=120}} \right.$

Resolviendo por el método de sustitución, que consiste en aislar en una ecuación una de las dos incógnitas para sustituirla en la otra ecuación, obtenes:

Despejando v0 de la primera ecuación:

$v0= \frac{90-2*a}{2}$

Reemplazando en la segunda ecuación:

$120=\frac{90-2*a}{2} *3+\frac{9}{2} *a$

Resolviendo:

$120=(90-2*a)*\frac{3}{2} +\frac{9}{2} *a$

$120=135-3*a +\frac{9}{2} *a$

$120-135=-3*a +\frac{9}{2} *a$

$-15=\frac{3}{2} *a$

$\frac{-15}{\frac{3}{2} } =a$

-10=a

Reemplazando el valor de a en la expresión despejada anteriormente obtenes:

$v0= \frac{90-2*(-10)}{2}$

Resolviendo:

$v0= \frac{90+20}{2}$

$v0= \frac{110}{2}$

v0=55

<u><em>La velocidad inicial es 55 </em></u> $\frac{m}{s}$ <u><em>y su aceleración es -10 </em></u> $\frac{m}{s^{2} }$ <u><em></em></u>

3 0

3 years ago

PLEASE ANSWER FAST!

Paraphin [41]

Answer:

0.36 g/cm3 I hope this helps

3 0

3 years ago

Read 2 more answers

Which word equation shows hydrogen reacting with oxygen to form water?

Karo-lina-s [1.5K]

2H₂ + O₂ = 2H₂O
_______________________

3 0

3 years ago

Anders Celsius made the __________

lisov135 [29]

Anders Celsius made the centigrade thermometer.

3 0

2 years ago