Which element has 7 valence electrons?

A. Sodium (Na)
B. Carbon (C)
C. Nitrogen (N)
D. Bromine (Br)

Answer:

 (C) Mechanical Force

Explanation:

Answer:

Wc = 7.84    weight of crown

Ww = 7.84 - 6.86 = .98       weight of water displaced

Density = 7.84 / .98 = 8     crown is 8 X that of water

Since gold has a density of 19.3 that of water the crown is certainly not 100 percent (if any) gold  

The work done by the force on the block is approximately 311.2 Joules.

To calculate the work done by the constant force of magnitude F = 45 N over a distance of 8 m at an angle of 30 degrees to the horizontal, we need to find the component of the force that acts parallel to the displacement.

The horizontal component of the force can be calculated using trigonometry:

F_horizontal = F * cos(angle)

            = 45 N * cos(30 degrees)

            = 45 N * (√3 / 2)

            ≈ 38.9 N

Now, we can calculate the work done by the force using the equation:

Work = Force * Distance * cos(theta)

where theta is the angle between the force and the displacement.

Work = F_horizontal * Distance * cos(0)

     = 38.9 N * 8 m * cos(0)

     = 38.9 N * 8 m

     = 311.2 Joules

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Answer:

100 m

Explanation:

1. The force between the two charges is 1.78 × 10⁻⁵ pounds, with opposite signs indicating attraction between the charges.

2. The resistance of 10 gauge aluminum wire over a 40 ft distance would be 0.506 ohms.

3. The cost of electricity from the automobile battery is 38.6 cents per kWh.

4. The current that would be carried through the body is 0.8 mA if dry.

1. The force between two point charges can be calculated using Coulomb's law, which states that the force is proportional to the product of the charges and inversely proportional to the square of the distance between them.

Using the values given, the force can be calculated as F = (k * q1 * q2) / r², where k is Coulomb's constant, q1 and q2 are the charges, and r is the distance between them. Plugging in the values, the force can be calculated as 1.78 × 10⁻⁵ pounds, with opposite signs indicating attraction between the charges.

2. The resistance of a wire is determined by its length, cross-sectional area, and resistivity. The resistivity of aluminum is higher than that of copper, so a larger cross-sectional area is required to achieve the same resistance. Using the gauge size conversion chart, 10 gauge aluminum wire has a cross-sectional area of 5.26 mm², which is approximately 83% of the cross-sectional area of 12 gauge copper wire.

Thus, the resistance of 10 gauge aluminum wire over a 40 ft distance can be calculated as R = (rho * L) / A, where rho is the resistivity of aluminum, L is the length, and A is the cross-sectional area. Plugging in the values, the resistance can be calculated as 0.506 ohms.

3. To calculate the cost of electricity per kWh, the total cost and the total amount of energy supplied must be known. Since the battery supplies 12 V and 51 A for one hour, the total energy supplied can be calculated as E = V * I * t, where V is the voltage, I is the current, and t is the time.

Plugging in the values, the total energy supplied can be calculated as 612 watt-hours (Wh). Since one kWh is equal to 1000 Wh, the total energy supplied can be converted to 0.612 kWh. Dividing the total cost by the total energy supplied gives the cost per kWh, which is 38.6 cents.

4. The current through the body can be calculated using Ohm's law, which states that current is equal to voltage divided by resistance. Using the values given, the resistance can be either 100,000 ohms or 300 ohms depending on whether the skin is dry or wet.

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Answer:

0.67m/s

Explanation:

Given parameters:

Distance  = 4m

Time taken  = 6s

Unknown:

Speed  = ?

Solution:

Speed is the distance covered per unit of time.

It is mathematically expressed as;

  Speed  = \(\frac{distance}{time}\)  

  Speed  = \(\frac{4}{6}\)    = 0.67m/s

Explanation:

density equals mass/volume

Answer:

 \(\mathrm{volume = \bf 31.33 \sapce\ cm^{-3}}\)

Explanation:

To calculate the volume, we can use the following formula:

\(\boxed{\mathrm{density = \frac{mass}{volume}}}\).

In this case,

• density = 0.798 gcm⁻³

• mass = 25 g

Substituting values into the formula:

\(\mathrm{0.798 \space\ gcm^{-3}= \frac{25 \space\ g}{volume}}\)

⇒ \(\mathrm{volume = \frac{25 \space\ g}{0.798 \space\ gcm^{-3}}}\)

⇒  \(\mathrm{volume = \bf 31.33 \sapce\ cm^{-3}}\)

Answer:

Explanation:

The electric flux through a surface is given by the equation:

Φ = EAcos(θ)

where Φ is the electric flux, E is the electric field, A is the area of the surface, and θ is the angle between the electric field and the surface normal.

We are given Φ = 4.44 N⋅m2/C, A = 6.66×10−4 m2, and θ = 60.0∘. Substituting these values into the equation above and solving for E, we get:

E = Φ / (Acos(θ))

= 4.44 N⋅m2/C / (6.66×10−4 m2cos(60.0∘))

= 1.62×10^4 N/C

Therefore, the magnitude of the electric field is 1.62×10^4 N/C.

The magnitude of the electric field is 13,320 N/C.

The electric flux through a surface is defined as the product of the electric field and the area of the surface projected perpendicular to the electric field. Mathematically, we can write:

Φ = EAcos(θ)

where Φ is the electric flux, E is the electric field, A is the area of the surface, and θ is the angle between the electric field and the surface normal.

Here in the Question,

We are given the electric flux Φ = 4.44 N·m^2/C, the area A = 6.66×10^-4 m^2, and the angle θ = 60.0°. We can solve for the magnitude of the electric field E by rearranging the equation as follows:

E = Φ / (A*cos(θ))

Substituting the given values, we get:

E = 4.44 N·m^2/C / (6.66×10^-4 m^2*cos(60.0°))

Simplifying the denominator, we get:

E = 4.44 N·m^2/C / (6.66×10^-4 m^2*0.5)

E = 13,320 N/C

Therefore, 13,320 N/C is the magnitude of the electric field.

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Answer:

I KNOW THE ANSWER IT WILL COST 30$

Explanation:

Kinetic energy is gotten from wind which is converted into rotational energy.

The wind is used to produce electricity using the kinetic energy created by air in motion wind turbines convert the kinetic energy in the wind into mechanical power. This mechanical ability can be used for particular tasks (such as grinding grain or forcing water) or can be converted into electricity by a generator. into electricity. In present wind turbines, wind rotates the rotor blades, which change kinetic energy into rotational energy. Wind turbines labor on an easy principle: in lieu of using electricity to make wind like a fan wind turbines use the wind to make electricity. The wind turns the rotter-like blades of a turbine around a rotor, which spins a generator, which produced electricity.

So we can conclude that Wind rotates the rotor blades that convert kinetic energy into rotational energy.

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Answer:

1.  SG  

true

=2.689

2. The object is probably some sort of minerals and rocks such as Feldspar, Corals, Beryl, etc.

Explanation:

Given:

mass in the air= 0.0675 kg

mass in water= 0.0424 kg

The specific gravity of the object will be 2.6892. It is the ratio of the density of the given fluid and the standard fluid.

Density is specified as the mass divided by the volume. It is represented by the unit of measurement as kg/m³.

The mass of the object in air;

m=Vρ₀

m=0.0675 kg

Buoyant force on the object;

B= Vρₐg

For equilibrium;

N+B=m₀g

n=m₀g-Vρₓg

N/g=m₀-Vρₓ

N/g=0.0424 kg

\(\rm \frac{V\rho_0}{V\rho_x} =\frac{0.0675 }{m_0-0.0424 \ kg} \\\\ \frac{\rho_0}{\rho_x} =\frac{0.0675}{0.0675-0.0424} \\\\ \frac{\rho_0}{\rho_x} =2.6892\)

Hence, the specific gravity of the object will be 2.6892.

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The speed of the roller coaster at the bottom of the hill if the track was frictionless is 34.04 m/s.

Given that the weight of the roller coaster is 2000 kg and the initial vertical drop of the ride is 59.3 m. We are to find the speed of the roller coaster at the bottom of the hill if the track was frictionless.We know that the roller coaster will lose potential energy due to the vertical drop. Assuming there is no friction, the potential energy will be converted into kinetic energy at the bottom of the hill.Considering the conservation of energy between the potential and kinetic energy, we can set the initial potential energy equal to the final kinetic energy. We can use the formula to calculate potential energy, which is PE = mgh where m = 2000 kg, g = 9.8 m/s², and h = 59.3 m. Therefore,PE = 2000 kg × 9.8 m/s² × 59.3 m = 1,157,924 JWe can use the formula to calculate kinetic energy, which is KE = 1/2mv² where m = 2000 kg and v is the final velocity. Therefore,KE = 1/2 × 2000 kg × v².The total energy remains constant as we know there is no friction. Therefore the final kinetic energy will be equal to the initial potential energy,1,157,924 J = 1/2 × 2000 kg × v²v² = (2 × 1,157,924 J) / 2000 kgv² = 1157.924v = √1157.924v = 34.04 m/s.

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The owner's velocity is in the opposite direction of the combined velocity of the dog and the cat, and its magnitude is approximately 0.916 m/s.

To solve the given problem, we can use the principle of conservation of momentum to find the direction and magnitude of the owner's velocity.

Let's denote the velocity of the dog as v1 (northward), the velocity of the cat as v2 (eastward), and the velocity of the owner as v (unknown).

According to the conservation of momentum, the total momentum before the interaction is equal to the total momentum after the interaction.

The total momentum before the interaction is given by:

Total momentum before = (mass of the dog * velocity of the dog) + (mass of the cat * velocity of the cat) + (mass of the owner * velocity of the owner)

Mass of the dog (m1) = 24.4 kg

Velocity of the dog (v1) = 2.14 m/s

Mass of the cat (m2) = 5.53 kg

Velocity of the cat (v2) = 3.56 m/s

Mass of the owner (m3) = 78.5 kg

Velocity of the owner (v) = unknown

Total momentum before = (24.4 kg * 2.14 m/s) + (5.53 kg * 3.56 m/s) + (78.5 kg * v)

The total momentum after the interaction is zero since the owner has the same momentum as the pets taken together.

Total momentum after = 0

Equating the two expressions:

(24.4 kg * 2.14 m/s) + (5.53 kg * 3.56 m/s) + (78.5 kg * v) = 0

Simplifying the equation:

(52.216 kg·m/s) + (19.6488 kg·m/s) + (78.5 kg * v) = 0

71.8648 kg·m/s + (78.5 kg * v) = 0

Solving for v:

78.5 kg * v = -71.8648 kg·m/s

v = -71.8648 kg·m/s / 78.5 kg

v ≈ -0.916 m/s

Therefore, the direction of the owner's velocity is opposite to the combined velocity of the dog and the cat, and the magnitude of the owner's velocity is approximately 0.916 m/s.

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Galileo challenged the Aristotelian-Ptolemaic model, providing support for the heliocentric model and paving the way for a new understanding of the universe.

Galileo Galilei played a crucial role in challenging the prevailing geocentric model of the universe proposed by Aristotle and supported by Ptolemy. He provided several lines of evidence that effectively disproved their theories and supported the heliocentric model proposed by Nicolaus Copernicus. Some of the key evidence used by Galileo includes:

1. Observations through a telescope: Galileo was one of the first astronomers to use a telescope to observe the heavens. His telescopic observations revealed several important discoveries that contradicted the Aristotelian-Ptolemaic worldview. He observed the phases of Venus, which demonstrated that Venus orbits the Sun and not Earth. He also observed the four largest moons of Jupiter, now known as the Galilean moons, which provided evidence for celestial bodies orbiting a planet other than Earth.

2. Sunspots: Galileo's observations of sunspots provided evidence that the Sun is not a perfect celestial body, as suggested by Aristotle. Sunspots indicated that the Sun has imperfections and undergoes changes, challenging the notion of celestial perfection.

3. Mountains on the Moon: Galileo observed the rugged and uneven surface of the Moon, which contradicted Aristotle's belief in celestial spheres made of perfect, unchanging material. The presence of mountains on the Moon suggested that celestial bodies are subject to the same physical laws as Earth.

4. Phases of Venus: Galileo's observations of the phases of Venus provided direct evidence for the heliocentric model. As Venus orbits the Sun, it goes through phases similar to the Moon, ranging from crescent to full. This observation strongly supported the idea that Venus revolves around the Sun.

These lines of evidence presented by Galileo challenged the Aristotelian-Ptolemaic model, providing support for the heliocentric model and paving the way for a new understanding of the universe. His work marked a significant turning point in the history of science and laid the foundation for modern astronomy.

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Answer:

The correct solution is "122.2211".

Explanation:

Given:

deceleration,

a = 22 ft/sec²

Initial velocity,

\(V_i=50 \ m/h\)

Now,

\(V_i=50 \ m/h\times 5280 \ ft/m\times hr/3600 \ s\)

    \(=73.333 \ ft/sec\)

Now,

Final velocity,

\(V_f=0\)

Initial velocity,

\(V_{initial} = 73.333 \ ft/sec\)

hence,

⇒ \(V_f^2=V_i^2+2aD\)

By putting the values, we get

      \(0=(73.333)^2+2\times( -22) D\)

  \(44D=(73.333)^2\)

      \(D=\frac{(73.333)^2}{44}\)

          \(=122.2211\)

Answer:

2 because I did this on before

Given:

Power for coffee maker = 1600 watts

Time indicated for the cofee maker = 10 minutes

Power for microwave = 1100 watts

Time indicated for the microwave = 4 minutes

Cost per hour of electrical appliances = $0.08 kwh

Let's find the total cost to use the appliances.

First convert the power to from watts to kilowatts by dividing by 1000.

Next step is to convert the time from minutes to hours:

Thus, to find the total cost to use the appliances, we have:

Solving further:

Therefore, the cost to use the appliances is $0.0272 which is approximately $0.03

ANSWER:

$0.0272

The Hubble sphere forms a sort of edge to our observable universe. This isn't a real edge to the universe because of its expanding nature. For this reason also,  this edge doesn't violate the cosmological principle or the Copernican principle.

In cosmology, the Hubble sphere is a spherical region of the observable universe that surrounds an observer and beyond which, as the universe expands, objects move away from that observer at a faster pace than the speed of light. Approximately 10^31 cubic light years make up the Hubble volume (or about 10^79 cubic meters).

Since the Hubble parameter varies across cosmological models, the Hubble limit typically does not coincide with a cosmological event horizon. For instance, in a decelerating Friedmann universe, the Hubble sphere expands with time and its border passes over light from more distant galaxies, allowing light that was released earlier by objects outside the Hubble volume to finally reach the sphere and be detected by observers.

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For the first 6 kg block, the speed after the collision will be 2.5 m/s. For the second 6 kg block, the speed after the collision will be zero since it sticks to the first 6 kg block.

Speed is a measure of how quickly an object moves or how quickly a task is performed. It is usually measured in units of distance per unit of time, such as metres per second, miles per hour, or kilometres per hour. Speed is an important concept in physics and is used to describe motion of all kinds, from elementary particles to everyday objects such as cars, planes, and rockets.

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Answer:

1. realizing of arrow

2. kicking of ball

3. punching the punching bag

The percentage error in a steel tape used for measurement on a cold day when the temperature is -5 ℃ is - 0.028

Coefficient of linear thermal expansion for steel, α = 1.1 * \(10^{-5}\) / C

Let the length of the tape at 20 ℃ be L.

New length of the steel tape after cooling, L' = L ( 1 + α ΔT )

ΔL = L' - L

ΔL = L ( 1 + α ΔT ) - L

ΔL = L ( 1 + α ΔT - 1 )

ΔL = L α ΔT

ΔT = T - \(T_{0}\)

T = Final temperature

\(T_{0}\) = Initial temperature

ΔT = - 5 - 20

ΔT = - 25 ℃

ΔL = L * 1.1 * \(10^{-5}\) * ( - 25 )

ΔL = - 27.5 * \(10^{-5}\)  * L

Percentage error = ΔL / L * 100

Percentage error =  - 27.5 * \(10^{-5}\)  * L / L * 100

Percentage error =  - 0.028

Therefore, the percentage error in the steel tape is - 0.028

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The concept of this question can be well understood by listing out the parameters given.

The purpose is to determine the spring constant.

Let us assume that the two blocks are Block A and Block B.

At point A on block A, the initial velocity on the block is zero

i.e. u = 0

We want to determine the time it requires for Block A to reach the table. The can be achieved by using the second equation of motion which can be expressed by using the formula.

\(\mathsf{S = ut + \dfrac{1}{2}gt^2}\)

From the above formula,

The distance (S) = 30 cm; we need to convert the unit to meter (m).

The acceleration (g) due to gravity = 9.8 m/s²

∴

inputting the values into the equation above, we have;

\(\mathsf{0.3 = (0)t + \dfrac{1}{2}*(9.80)*(t^2)}\)

\(\mathsf{0.3 = \dfrac{1}{2}*(9.80)*(t^2)}\)

\(\mathsf{0.3 =4.9*(t^2)}\)

By dividing both sides by 4.9, we have:

\(\mathsf{t^2 = \dfrac{0.3}{4.9}}\)

\(\mathsf{t^2 = 0.0612}\)

\(\mathsf{t = \sqrt{0.0612}}\)

\(\mathbf{t =0.247 \ seconds}\)

However, block B comes to an instantaneous rest on point C. This is achieved by the dropping of the block on the spring. During this process, the spring is compressed and it bounces back to oscillate in that manner. The required time needed to get to this point C is half the period, this will eventually lead to the bouncing back of the block with another half of the period, thereby completing a movement of one period.

By applying the equation of the time period of a simple harmonic motion.

\(\mathbf{T = 2 \pi \sqrt{\dfrac{m}{k}}}\)

where the relation between time (t) and period (T) is:

\(\mathsf{t = \dfrac{T}{2}}\)

T = 2t

T = 2(0.247)

T = 0.494 seconds

\(\mathbf{T = 2 \pi \sqrt{\dfrac{m}{k}}}\)

By making the spring constant (k) the subject of the formula:

\(\mathbf{\dfrac{T}{2 \pi } = \sqrt{ \dfrac{m}{k}}}\)

\(\Big(\dfrac{T}{2 \pi }\Big)^2 = { \dfrac{m}{k}\)

\(\dfrac{T^2}{(2 \pi)^2 }= { \dfrac{m}{k}\)

\(\mathsf{ T^2 *k = 2 \pi^2*m} \\ \\ \mathsf{ k = \dfrac{2 \pi^2*m}{T^2}}\)

\(\mathsf{ k =\Big( \dfrac{(2 \pi)^2*(51 \times 10^{-3})}{(0.494)^2} \Big) N/m}\)

\(\mathbf{ k =8.25 \ N/m}\)

Therefore, we can conclude that the spring constant between the two 51 g blocks held at a distance 30 cm above a table as a result of instantaneous rest caused by the compression of the spring is 8.25 N/m.

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Answer:

Explanation:

Part A:

Using conservation of energy, we can find the speed of the trampoline artist just before he lands on the trampoline. At the top of the platform, he has gravitational potential energy equal to mgh, where m is his mass, g is the acceleration due to gravity, and h is the height of the platform. At the bottom of his jump, he has kinetic energy equal to (1/2)mv^2, where v is his speed just before he lands on the trampoline. We can equate these two energies and solve for v:

mgh = (1/2)mv^2

v = sqrt(2gh)

where h = 2.0 m and g = 9.81 m/s^2. Plugging in the values, we get:

v = sqrt(2(9.81 m/s^2)(2.0 m)) = 6.26 m/s

Therefore, the trampoline artist is going 6.26 m/s as he lands on the trampoline.

Part B:

The force exerted by the trampoline on the artist is equal to the weight of the artist, which is mg, where g is the acceleration due to gravity. This force causes the trampoline to compress a distance d, which we want to find. From Hooke's law, we know that the force exerted by a spring is equal to its spring constant times its deformation from its equilibrium length. Therefore:

mg = kd

where k is the spring constant of the trampoline. Solving for d, we get:

d = (mg)/k

where m = 75 kg, g = 9.81 m/s^2, and k = 6.7×10^4 N/m. Plugging in the values, we get:

d = (75 kg)(9.81 m/s^2)/(6.7×10^4 N/m) = 0.109 m

Therefore, the trampoline depresses 0.109 m when the artist lands on it.

If the child is holding the toy car still for 30 seconds, then net work done on the car is zero.

Work is defined as the product of force and displacement in the direction of force. In this case, the force and displacement are perpendicular to each other, so no work is being done. Therefore, net work done on the toy car is zero.

If the child is holding the toy car still, then net work done on the car is zero. This is because the force exerted by the child is equal in magnitude and opposite in direction to the force of gravity acting on the car and car is not moving, so there is no displacement.

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Answer:

Explanation:

My perdiction was correct. I predicted in Part A that the Kinetic Energy would increase. In Part B I predicted that the potential energy would decrease due to the kinetic energy increasing.

The final velocity of the red ball is 18 m/s.

The term momentum has to do with the product of the mass and the velocity of an object We know that the momentum is always conserved in accordance with the Newton third law. Also it is clear that the momentum before collision is equal to the total momentum after collision and we are going to apply this principle here.

Then;

Mass of the blue ball =  6 kg

Mass of the red ball =  1 kg

Initial velocity of the blue ball =  4 m/s

Initial velocity of the red ball = 0 m/s

Final velocity of the red ball = ??

Final velocity of the blue ball =  1 m/s

We now have;

(6 * 4) + (1 * 0) = (1 * v) + (6 * 1)

24 = v + 6

v = 24 - 6

v = 18 m/s

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Answer:

This question is not complete but the completed question is below

Which statement is not correct for lamps connected in parallel?

A They can be switched on and off separately.

B They will remain bright if another lamp is connected in parallel.

C They share the supply voltage equally between them.

D They still operate if one lamp is removed.

The correct option is A

Explanation:

Lamps connected in series have the same voltage running across each lamp in the connection and will thus have the same brightness if any lamp is added or removed. This property also means they can only be switched on and off by a single switch, hence option A is not correct about lamps connected in parallel.

Lamps connected in a parallel circuit will have the same voltage and different current.

A parallel circuit contains resistors arranged parallel to each other. some basic characteristics of parallel circuit include the following;

V = I₁R₁ + I₂R₂ + I₃R₃ + ---

where;

Thus, we can that lamps connected in a parallel circuit will have the same voltage and different current.

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Answer:

inertia

Explanation: