Indoor pollution experts conducted an analysis of the paint used in many office buildings which revealed that the paint contains traces of lead. The lead seems to rise to the surface of the paint and escape into the building's air supply. Tests show that because of the chemical drying process, the lead is not discernible on the surface until the paint has been on the walls for at least six months. To meet safety standards, owners should repaint walls at least every six months, or cover the walls with a different material.Which of the following, if true, would most weaken the conclusion above?A) The indoor pollution experts had no clear understanding of why it took six months for the lead to become discernible on the paint's surface.B) The indoor pollution experts neglected to examine the paint for traces of other toxic substances such as cadmium and mercury.C) The amount of lead found on the surface of the paint after six months remained constant for the next two years.D) The indoor pollution experts found that even in those offices painted with a different brand of paint, traces of lead were still found in the air workers breathed.E) The indoor pollution experts' research shows that the amounts of lead that come into contact with the air people breathe, even in the office buildings that used the greatest amount of paint, are too low to affect workers.

Answers

Answer 1

Answer:

E) The indoor pollution experts' research shows that the amounts of lead that come into contact with the air people breathe, even in the office buildings that used the greatest amount of paint, are too low to affect workers

Explanation:

The conclusion that would weaken the above statement if true was that the amount of lead found in air was not hazardous for the people living in building and the effects of such paint was quite low o affect workers.

Related Questions

A skipper on a boat notices wave crests passing his anchor chain every 5.6 s . He estimates the distance between wave crests to be 16 m . He also correctly estimates the speed of the waves. Find this speed.

Answers

Answer:

v = 2.85 m/s

Explanation:

Given that,

A skipper on a boat notices wave crests passing his anchor chain every 5.6 s.

The distance between wave crests to be 16 m.

We need to find the speed of the waves. The speed of a wave can be calculated by the formula as follows :

[tex]v=f\lambda\\\\v=\dfrac{\lambda}{T}\\\\v=\dfrac{16}{5.6}\\\\v=2.85\ m/s[/tex]

So, the speed of the wave is 2.85 m/s.

Hess's law states that:

A. Energy cannot be created nor destroyed, it can only change form.
B. The enthalpy change when 1 mole of a substance undergoes complete combustion under standard conditions is equal to molar masses of the compounds.
C. When the enthalpy changes under standard conditions, 1 mole of a substance is formed from its elements.
D. The overall enthalpy change for a reaction is independent of the route the reaction takes.

Answers

Answer:

D. The overall enthalpy change for a reaction is independent of the route the reaction takes.

Answer: Hess's law states that the overall enthalpy change for a reaction is independent of the route the reaction takes. Option D is correct.

It is given Hess's law.

It is required to state the Hess's law.

What is Hess's law ?

Thermochemical equations can be manipulated to give the data chemical reactions. We find exactly how much energy will be absorbed or released by the reaction because we may face various explosions.

There are mainly two ways to calculate ΔH of any reaction. First If the reaction has ΔH then the reverse of the reaction will have opposite ΔH and the second is if double the ΔH of the substances, double the ΔH.

Therefore Hess's law states that the overall enthalpy change for a reaction is independent of the route the reaction takes.

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In a lunar experiment, a 950-g aluminum (920 J/(°Ckg)) sphere is dropped from the space probe while is 75 m above the Lunar ground. If the sphere’s temperature increased by 0.11°C when it hits the ground, what percentage of the initial mechanical energy was absorbed as thermal energy by the aluminum sphere?

Answers

Answer:

13.759 % of the initial mechanical energy is lost as thermal energy.

Explanation:

By the First Law of Thermodynamics we know that increase in internal energy of the object ([tex]U[/tex]), in joules, is equal to the lost amount of the change in gravitational potential energy ([tex]U_{g}[/tex]), in joules:

[tex]\frac{x}{100} \cdot \Delta U_{g} = \Delta U[/tex] (1)

Where [tex]x[/tex] is the percentage of the energy loss, no unit.

By definition of the gravitational potential energy and internal energy, we expand this equation:

[tex]\frac{x\cdot m \cdot g \cdot h}{100} = m\cdot c\cdot \Delta T[/tex] (1b)

Where:

[tex]m[/tex] - Mass of the object, in kilograms.

[tex]g[/tex] - Gravitational acceleration, in meters per square second.

[tex]h[/tex] - Initial height of the object above the lunar ground, in meters.

[tex]c[/tex] - Specific heat of aluminium, in joules per degree Celsius-kilogram.

[tex]\Delta T[/tex] - Temperature increase due to collision, in degree Celsius.

If we know that [tex]m = 0.95\,kg[/tex], [tex]g = 9.807\,\frac{m}{s^{2}}[/tex], [tex]h = 75\,m[/tex], [tex]c = 920\,\frac{J}{kg\cdot ^{\circ}C}[/tex] and [tex]\Delta T = 0.11\,^{\circ}C[/tex], then the percentage of energy loss due to collision is:

[tex]x = \frac{100\cdot c\cdot \Delta T}{g\cdot h}[/tex]

[tex]x = \frac{100\cdot \left(920\,\frac{J}{kg\cdot ^{\circ}C} \right)\cdot (0.11\,^{\circ}C)}{\left(9.807\,\frac{m}{s^{2}} \right)\cdot (75\,m)}[/tex]

[tex]x = 13.759\,\%[/tex]

13.759 % of the initial mechanical energy is lost as thermal energy.

What is the centripetal acceleration of a point on the perimeter of a bicycle wheel diameter 70.0 cm when the bike is moving 8.0 m/s? (160 m/s)

Answers

It’s 180 m/s^2 dude. I think I have you in my class lol.

The centripetal acceleration of an object is due to the changing velocity in a circular path and the centripetal acceleration of the bicycle is 182.85 m/s².

What is Centripetal acceleration?

Centripetal acceleration of an object can be defined as the property of the motion of an object which is traversing a circular path. Any object which is moving in a circular path and has an acceleration vector pointed towards the center of that circular path is known as Centripetal acceleration.

The centripetal acceleration of an object can be calculated by the formula:

ac = v²/ r

where, ac = centripetal acceleration,

v = velocity of the object,

r = radius of the circular path

The centripetal acceleration of the object will be:

ac = (8)²/ r

radius = diameter/ 2

radius = 70/ 2

radius = 35cm or 0.35 m

ac = 64/ 0.35

ac = 182.85 m/s²

Therefore, the centripetal acceleration of the bicycle will be 182.85 m/s².

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Given: F = k· m. g
Solve for "k"

Answers

Answer:

[tex]F = kmg \\ k = \frac{F}{mg} [/tex]

Explanation:

F = k . m . g

=> F = k . mg

[tex] = > k = \frac{F}{mg} (ans)[/tex]

can someone help me asap please​

Answers

Answer:

Resultant force is 20 N

Explanation:

Resolving vertically:

[tex]{ \sf{F_{y} = (8 \cos 30 \degree) + (12 \cos 30 \degree) }} \\ { \sf{ \sum F_{y} = 17.3 \: newtons }}[/tex]

Resolving horizontally:

[tex]{ \sf{F_{x} = (8 \sin 30 \degree) + (12 \sin 30 \degree) }} \\ { \sf{ \sum F _{x} = 10 \: newtons}}[/tex]

Resultant force:

[tex]{ \boxed{ \bf{F = \sqrt{ {F _{x} }^{2} + {F _{y} }^{2} } }}} \\ { \sf{F = \sqrt{ {17.3}^{2} + {10}^{2} } }} \\ { \sf{F = \sqrt{399.29} }} \\ F = 19.98 \approx20 \: newtons[/tex]

what is required for force to come into play​

Answers

Answer:

An interaction of one object with another object results in a force between the two objects. Thus, at-least two objects must interact for a force to come into play.

the slope of a line on a position vs time graph is the

a. velocity
b. time
c. distance
d. displacement

Answers

It's the velocity, but only the magnitude. It can't show the direction of the velocity. So it's better to call it speed.

A 4000 N force acts on an object that initially has a momentum of 400 kg-m/s for 0.9 seconds. What is the final momentum of the system?

Answers

Answer:

4360 Kgm/s

Explanation:

Applying,

Ft = M-M'................. Equation 1

Where F = force, t = time, M = Final momentum, M' = Initial momentum.

make M the subject of the equation

M = Ft+M'............ Equation 2

From the question,

Given: F = 4000 N, t = 0.9 seconds, M' = 400 kg-m/s

Substitute these values into equation 2

M = 4000+(0.9×400)

M = 4000+360

M = 4360 kgm/s

Hence the final momentum is 4360 kgm/s

in a cathode-ray tube, particles are fired at the screen. What are these particles

Answers

Thomson's experiments with cathode ray tubes showed that all atoms contain tiny negatively charged subatomic particles or electrons.

"Measurement is essential in our life. Justify the statement.​

Answers

Explanation:

Measurement plays an important role in our daily lives because they are useful to do basic tasks, such as taking the temperature of a child with the help of a thermometer,making time estimations,measure out medicines and find out weights, areas and volumes of different substances

Why does a small piece of steel rod sinks while a large steel oil tanker floats?

Plss help thanks! pls include EXPLANATION and EXAMPLES that I can proof to people that has no knowledge ​

Answers

Answer:

Too what i know its because of the air

Explanation:

The steel rod is more dense and doesnt have air whil'st the oil tanker is less dense with lots of air

a teacher drives from school to the mall. then she goes to the doctors office for a physical examination. what is the magnitude of her displacement

Answers

The magnitude of the teachers displacement is the difference between

the location of the school and the location of the doctors office

The reason behind the above expression are explained as follows

The known locations of the teacher;

Initial location; The school

Second location; The mall

The eventual location; The doctors office

The required information;

The magnitude of the teachers displacement

The method of obtaining the displacement of the teacher;

Qualitatively, the displacement of the teacher can be obtained by applying the definition of displacement as follows;

The definition of displacement is an object's change in position, given by the difference between its start and finish locations

According to the definition of displacement, therefore, the magnitude of

the teachers displacement is the distance between the school and the

doctors office which is given by the difference between the coordinates of

the location of the school and the location of the doctors office

The magnitude of the displacement of the teacher = The coordinate of the location of the doctors office - The coordinate of the location of the school

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A city bus travels along its route from Jackson Street 8 km to Aurora Avenue, where it turns and continues 13 km.
 
What is the total distance that the bus has traveled? km
 
The total displacement of the bus is approximately 15 km northeast northwest southeast southwest.

Answers

im a bit confused on what the question is:(

if its just asking for the total number of km traveled it would be 21 km

A 210 Ohm resistor uses 9.28 W of power. How much current flows through the resistor? (unit=A)

Answers

Answer:

.21

Explanation:

i see everyone got it wrong so ill give you the answer, good luck :)

.............................

Answers

Dot, dot, dot, dot, lol

A group of students are designing a field study to investigate the length of time a traffic light remains yellow.

Answers

Answer:

3 to 7 seconds.

Explanation:

According to the traffic engineers the length or the duration of the signal to turn form yellow or amber to green is more than 5 seconds. A time interval is needed to easy out the traffic flow.

Difference between gravitational force and frictional​

Answers

Explanation:

gravitational force or gravity is the force of attraction between objects that have mass.

frictional force is the forec that opposes motion (movement) when two surface are in contact. (acts in the opposite direction of motion)

so to sum it up,

- gravtional force is the force of attraction between objects that have mass.

- objects on the earth have weight because of gravitational force between them and the earth.

frictional force

- oppose motion

- slow down and stop moving objects and;

- produce heat

hope it helps :)

Answer: the difference is that they are 2 completely separate things

factor that affect gravitation

Answers

1) Two major factors, mass and distance, affect the strength of gravitational force on an object.

2) Most common factors that affect gravity are mass of the body, distance from centers, shape of bodies,etc. Gravity is a binding force, always acting to bind any material closure and closure inwards. If we think this way, then gravity is maximum at its centre and decreases slowly away from its centre.

hope it helps you

mark my answer as brainlist and follow

have a nice day

Tick (3) the correct statement about electrostatic charges.
(a) Earthing causes positive charges to flow from the object to the ground.
(b) Similar types of electric charges attract one another.
(c) An electroscope is used to determine the presence of electrostatic charges.

Answers

Answer:

similar type of electric charges attract one another

I think this is a coorect staement

Answer:

C ) An electroscope is used to determine the presence of electrostatic charges

Ploughing field with harrow pulled by a tractor is a modern technology​

Answers

Ploughing field with harrow pulled by a tractor being a modern technology​ is true.

What is Technology?

This involves the use of scientific knowledge to tackle different life problems and has different sectors.

Ploughing field with harrow pulled by a tractor involves machines and not manual labour which makes it a modern technology.

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D 2. Which of the following is an example of a specific goal?
O I want to lose weight.
I want to get stronger.
O I want to be able to walk one mile in 15 minutes.
I want to improve my speed.

Answers

I want to improve my speed

Answer:

D

Explanation:

1. Una carga Q1 = + 12 μC se coloca a una distancia r = 0.024 m desde una carga Q2 = + 16 μC. a) Determina la magnitud de la fuerza electrostática que actúa sobre las dos cargas, Q1 y Q2. b) ¿Es la fuerza la atracción o repulsión? 2. Determina la intensidad del campo eléctrico a una distancia radial de r = 48 mm desde una carga de Q = 24 μC. 3. Una carga Q1 = 24 mC se coloca a una distancia r = 0.032 m desde una carga Q2 = - 12 μC. a. Determina la cantidad de energía potencial eléctrica que tiene la carga Q1. b. Determina el potencial eléctrico en la posición de Q2.

Answers

Answer:

1. a. 3,000 N

b. Repulsión

2. 46.875 × 10⁶ N/C

3. a. 81,000 J

b. 6.75 × 10⁹ V

Explanation:

1. Los parámetros dados son;

Q₁ = +12 μC, Q₂ = +16 μC

La distancia entre las cargas, r = 0.024

La magnitud de la fuerza electrostática, F, entre cargas se da como sigue;

[tex]F = k \times \dfrac{Q_1 \cdot Q_2}{r^2}[/tex]

Donde, k = constante de Coulomb = 9.0 × 10⁹ N · m² / C²

Por lo tanto, obtenemos;

F = 9.0 × 10⁹ × 12 × 10⁻⁶ × 16 × 10⁻⁶ / 0.024² = 3.000

La magnitud de la fuerza electrostática, entre las cargas, F = 3000 N

(b) Dado que tanto Q₁ como Q₂ son cargas positivas, y las cargas iguales se repelen entre sí, la fuerza es la repulsión.

2) La intensidad de un campo eléctrico, E, se da como sigue;

[tex]E = \dfrac{k \cdot Q}{r^2}[/tex]

La magnitud de la carga, Q = 24 μC

La distancia donde se mide el campo, r = 48 mm = 0.048 m

Por lo tanto, E = 9.0 × 10⁹ × 12 × 10⁻⁶ / 0.048² = 46,875,000 N / C

La intensidad de un campo eléctrico, E = 46,875,000 N / C = 46.875 × 10⁶ N / C

3. La magnitud de las cargas son;

Q₁ = 24 mC

Q₂ = -12 μC

La distancia entre las cargas, r = 0.032 m

un. El potencial eléctrico de una carga, [tex]U_E[/tex] , se da de la siguiente manera;

[tex]U_E = k \times \dfrac{Q_1 \cdot Q_2}{r}[/tex]

Por lo tanto;

[tex]U_E[/tex] = 9.0×10⁹ × 24 × 10⁻³ × (-12) × 10⁻⁶ /0.032 = -81,000

La energía potencial eléctrica entre la carga, Q₁ y Q₂= -81,000 J

b. El potencial eléctrico de Q₁ en Q₂, V₁ = [tex]k \times \dfrac{Q_1 }{r}[/tex]

Por lo tanto, V₁ = 9.0×10⁹ × 24 × 10⁻³/0.032 = 6.75 × 10⁹

El potencial eléctrico de Q₁ en Q₂, V₁ = 6.75 × 10⁹ V

A ball is dropped from the roof of a 25-m-tall building. What is the velocity of the object when it touches the ground? Suppose the ball is a perfect golf ball and it bounces such that the ve locity as it leaves the ground has the same magnitude but the op posite direction as the velocity with which it reached the ground How high will the ball bounce? Now suppose instead that the ball bounces back to a height of 20 m. What was the velocity with which it left the ground?

Answers

Answer:

a)  [tex]h=25m[/tex]

b)  [tex]v=19.8m/sec[/tex]

Explanation:

From the question we are told that:

Height [tex]h=25m[/tex]

Bounce Height [tex]h'=20m[/tex]

Generally the Kinematic equation is mathematically given by

[tex]V=\sqrt{2gh}\\\\V=\sqrt{2*9.81*25}[/tex]

[tex]V=22.1m/sec[/tex]

Therefore Height

[tex]h=\frac{V^2}{2g}\\\\h=\frac{22.1^2}{2*9.81}[/tex]

[tex]h=25m[/tex]

b)

Generally the Kinematic equation is mathematically given by

[tex]v^2=2ah[/tex]

[tex]v^2=2*9.8*20[/tex]

[tex]v=\sqrt{2*9.8*20}[/tex]

[tex]v=19.8m/sec[/tex]

define Archemedics principle?​

Answers

THIS IS YOUR ANSWER :

Archimedes’ principle, physical law of buoyancy, discovered by the ancient Greek mathematician and inventor Archimedes, stating that any body completely or partially submerged in a fluid (gas or liquid) at rest is acted upon by an upward, or buoyant, force, the magnitude of which is equal to the weight of the fluid displaced by the body.

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Assuming Faraday constant to be 96500c/mol and relative atomic mass of copper 63,calculate the mass of copper liberated by 2A current in 5min.ans 0.196gm ​

Answers

Answer: The mass of copper liberated is 0.196 g.

Explanation:

The oxidation half-reaction of copper follows:

[tex]Cu\rightarrow Cu^{2+}+2e^-[/tex]

Calculating the theoretical mass deposited by using Faraday's law, which is:

[tex]m=\frac{M\times I\times t(s)}{n\times F}[/tex] ......(1)

where,

m = actual mass deposited = ? g

M = molar mass of metal = 63 g/mol

I = average current = 2 A

t = time period in seconds = 5 min = 300 s (Conversion factor: 1 min = 60 sec)

n = number of electrons exchanged = 2

F = Faraday's constant = 96500 C/mol

Putting values in equation 1, we get:

[tex]m=\frac{63 g/mol\times 2A\times 300s}{2\times 96500 C/mol}\\\\m=0.196g[/tex]

Hence, the mass of copper liberated is 0.196 g.

86,400 seconds into day​

Answers

Answer:

60×60×24=86,400

Explanation:

i.e. 86,400 secs is 1 day

1 hour = 60 minutes

1 minute = 60 seconds

1 day = 24 hours

60 min. × 60 sec. × 24 hr.

60 × 60 × 24 = 86,400 seconds

∴ 86,400 seconds = 1 day

a sphere of diameter 6.0
cm is moulded into a thin wire of diameter 0.2 mm calculate the length of the wire in metres ​

Answers

Answer:

V1 = 4/3 pi R^3 = pi D^3 / 6     D = 2 R       volume of sphere

V2 = pi r^2 L = pi d^2 L / 4       volume of wire

V2 / V1 = 1 = 3/2 d^2 L / D^3     since volumes are equal

L = 2/3 D^3 / d^2 = 2/3 * 6^3 / .02^2 = 360,00 cm = 3600 m

which two phenomena make up electromagnetism?

A) moving charges in an electric current attract each other
B) permanent magnets form a magnetic field from one pole to the other pole
C) an electric current causes a magnetic field around a core of magnetic metal
D) a moving magnet causes an electric current in a magnetic metal

Answers

Explanation:

the correct answer is option ( C ) and ( D )

A liquid has a density of 2 g/mL, the volume is measured at 20 mL, what is the mass of the liquid?

Answers

Answer: 40 grams, if it is two grams per mL and you have 20 mL, you multiply 2 grams/mL and you get the answer

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