Which substance is an example of an element? bronze copper methane rust

Answer:

false

Explanation:

Work may be done in positive or negative direction. When a work is done in positive direction, it is called useful work, when work is done in negative direction, it is known as useless work. Any energy associated with friction produces useless work. That is, the work is done in negative direction.

Therefore, thermal energy produced by friction can be used to do work but in negative direction.

The correct option is false.

Answer:

D. The net force is zero, so the acceleration is zero

Explanation:

In a simple harmonic motion, velocity and acceleration are out-of-phase as follows:

- When the displacement is zero (so, when the spring is in equilibrium position), the acceleration is zero, because the force is zero. In fact, the force is given by Hook's law:

[tex]F=-kx[/tex]

So, when x=0, F=0, and the acceleration is also zero according to Newton's second law:

[tex]a=\frac{F}{m}=0[/tex]

Instead, the velocity is maximum. In fact, the total mechanical energy (sum of kinetic and elastic potential energy) is constant, and since the elastic potential energy:

[tex]U=\frac{1}{2}kx^2[/tex]

is zero at x=0, this means that the kinetic energy is maximum. But the kinetic energy is

[tex]K=\frac{1}{2}mv^2[/tex]

and so, the velocity is also maximum.

- When the displacement is maximum, it is the opposite: the acceleration is maximum (because x is maximum, so the force is maximum), while the velocity is zero, because the elastic potential energy is maximum and so the kinetic energy is zero).

At point D, we are in the first situation (the spring is passing its position of equilibrium, so x=0), therefore the net force is zero and the acceleration is zero.

Answer:

D: The net force is zero, so the acceleration is zero

Explanation:

Answer:

1250 SQUARE YARDS

Explanation:

The area of the soccer field given the data from the question is 1250 yard²

Area = Length × Width

Area = Length × Width

Area = 50 × 25

Area = 1250 yard²

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The final potential difference across the capacitor after delivering 40% of its stored energy to a lamp is approximately 9.49V.

The question asked is related to the energy stored in a capacitor and its link to the potential difference across it. The energy stored in a capacitor is given by the relation Uc = CV²/2, where C is the capacitance and V is the potential difference. When a capacitor delivers 40% of its stored energy to a lamp, this means a reduction in the stored energy and therefore a corresponding reduction in potential difference as well.

As the stored energy is directly proportional to the square of the potential difference, if the energy reduces to 60% (after delivering 40%), the final potential difference will be the square root of this fraction (sqrt(0.6)) times the initial potential difference. The final potential difference across the capacitor will therefore be sqrt(0.6) * 12V, which is approximately 9.49V.

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To find the average speed of Amil's trip to the outlook, we convert the distance and time units and use the formula Average Speed = Distance / Time. The average speed of Amil's trip is 22.35 meters per second (rounded to the nearest hundredth).

To find the average speed of Amil's trip, we can use the formula:

Average Speed = Distance / Time

Amil drove 25 miles in 30 minutes to get to the outlook. To convert the distance from miles to meters, we use the conversion factor: 1 mile = 1609 meters. So, 25 miles is equal to 25 x 1609 = 40225 meters. To convert the time from minutes to seconds, we multiply 30 minutes by 60 to get 1800 seconds. Now we can calculate the average speed:

Average Speed = 40225 meters / 1800 seconds

Average Speed = 22.35 meters per second (rounded to the nearest hundredth).

Answer:

The answer would be The number of protons and neutrons

Neutrons and protons cannot be removed from nucleus from chemical reactions because they are strongly held together but nuclear reactions are strong enough to separate them

Explanation:

Nuclear reactions involve a change in the nucleus of an atom, usually producing a different element. Chemical reactions, on the other hand, involve only a rearrangement of electrons and do not involve changes in the nuclei

Galaxy is "all-encompassing" of the other words given so it doesn't belong.

A galaxy is a collection of stars, stellar remnants, interstellar gas, dust, and dark matter that is gravitationally bound. The name comes from the Greek word galaxias, which translates to mean "milky" and refers to the Milky Way galaxy, which houses the Solar System.

Given in the question  word doesn't belong: planet, galaxy, sun, moon

So, we can see "galaxy" is "all-encompassing" of the other words given, so it does not belong.

Galaxy is "all-encompassing" of the other words given so it doesn't belong.

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The momentum of the large rock that has a mass of 50kg and is rolling downhill at 3 m/s is 150kgm/s.

HOW TO CALCULATE MOMENTUM:

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The object that provides an inertial frame of reference is the skydiver falling at terminal velocity, as it is a scenario where the object moves at constant velocity with no net external force acting upon it.

An inertial frame of reference is defined as a reference frame in which an object either remains at rest or moves at a constant velocity, provided no external forces are acting upon it. Among the options given, the skydiver falling at terminal velocity provides an inertial frame of reference. Terminal velocity is a constant speed reached by an object when the drag force from the air resistance is equal to the force of gravity, causing no net force on the skydiver and thus no acceleration. The other objects are either accelerating or experiencing changing velocities which disqualify them as inertial reference frames.

Answer: The largest known star in the universe is UY Scuti, a hypergiant with a radius around 1,700 times larger than the sun. And it's not alone in dwarfing Earth's dominant star.

Explanation:

Answer:

The standard unit used to measure of mass is gram.

(2) is correct option.

Explanation:

S.I is the standard international system of unit.

The S.I unit of mass is kilogram.

1 kg = 1000 gm

So, We can say that,

The standard unit used to measure mass is gram.

Cubic meter is the unit of volume.

Liter is the unit of water.

Meter is the unit of length.

Hence,  The standard unit used to measure of mass is gram.

The purpose of biofeedback is to help subjects "control their internal processes".

Biofeedback is a kind of treatment that utilizes sensors joined to your body to gauge key body capacities. Biofeedback is expected to enable you to take in more about how your body functions. This data may assist you with developing better power over certain body capacities and address wellbeing concerns.  

This feedback causes you center around rolling out inconspicuous improvements in your body, for example, loosening up specific muscles, to accomplish the outcomes you need, for example, decreasing agony. Generally, biofeedback enables you to utilize your musings to control your body, frequently to enhance a wellbeing condition or physical performance.

In this hydroelectric energy system, mechanical energy from the moving water turns the turbine, generating electrical energy. This electrical energy is then transformed into thermal energy, increasing the water's temperature. The water eventually becomes steam and releases more thermal energy into the atmosphere.

In this system, mechanical energy from the moving water of the faucet turns the turbine. The mechanical energy of the spinning turbine generates electrical energy which is transformed into thermal energy that causes the temperature of the water to increase. The water then becomes steam and gives off more thermal energy into the atmosphere.

To calculate the energy of X-rays with a frequency of 3.00 × 10^16 Hz, use Planck's equation to find it to be approximately 124 eV.

The energy of X-rays with a frequency of 3.00 × 10^16 Hz can be calculated using Planck's equation:

E = hf

Given h (Planck's constant) = 6.626 × 10^-34 J-s and f (frequency) = 3.00 × 10^16 Hz, you can calculate the energy:

E = (6.626 × 10^-34 J-s) × (3.00 × 10^16/s) = 1.99 × 10^-17 Joules. Convert this to electron volts by dividing by the charge of an electron:

1 eV = 1.602 × 10^-19 Joules, so:

1.99 × 10^-17 J ÷ (1.602 × 10^-19 J/eV) ≈ 124 eV

Therefore, the correct answer is B) 124 eV.

Electronegativity is measured on a relative, dimensionless scale known as the Pauling scale. The scale is based on the ability to attract electrons when forming covalent bonds, with fluorine set at 3.98 and other elements scaled against this value. The Pauling scale is the standard despite the abstract nature of electronegativity.

Electronegativity is measured on a relative scale called the Pauling scale. This scale was developed by Linus Pauling in the 1930s. On the Pauling scale, which is the most commonly used scale for measuring electronegativity, electronegativity is dimensionless and has no unit of measure. Fluorine, the most electronegative element, is set at a value of 3.98. All other elements are assigned values from 0 to 4.0 based on their relative ability to attract a bonding pair of electrons compared to fluorine.

The notion of electronegativity is crucial in understanding the chemical behavior of elements, particularly in the formation of covalent bonds. The higher the electronegativity value of an element, the more strongly it tends to attract bonding electrons. Fluorine's high electronegativity makes it an important reference point against which the electronegativities of other elements are measured.

Since electronegativity is an abstract property and cannot be measured directly, the Pauling scale is based on observable quantities such as the strengths of covalent bonds and molecular dipole moments. Different scales may use various methodologies, but the Pauling scale remains the standard for discussed trends in electronegativity.

Answer:

a=0 m/s2

Explanation:

t=3,7 h=13320 s

v=const=71 km/h=19,7222 m/s ( 71*1000 m/2600 s=19,7222222 m/s)

if the speed is constant

a=Δv/Δt

since Δv= 0m/s since the speed is constant...

if the speed would rise from 0 m/s to 19.72222m/s

then a=(19.7222 m/s)/13320 s

a=0.00148 m/s2

A car travels in a straight line for 3.7 h at a constant speed of 71 km/h . what is its acceleration? answer in units of m/s 2

The Answer is Pressure hope it helps