Danielle is doing some diy. she uses a 1.2kw electric saw for 20 minutes and then a 1000w electric sander for half an hour. which job is the more expensive in terms of electricity used - sawing or sanding?

To refine minerals best describes the purpose of the process mentioned and is denoted as option B.

Thi involves the different processes involved in the purification of the elements found in the earth.

Refining materials usually starts with crushing and ends with dewatering to drain water.

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An audience member covers her ears during a loud concert shows evidence that matter can reflect waves.

An audience member covers her ears during a loud concert is an event that provides evidence that matter can reflect waves because a sound is heard again and again due to the reflection of waves. This repetition of sound is due to the property of reflection of sound waves.

So we can conclude that an audience member covers her ears during a loud concert shows evidence that matter can reflect waves.

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Answer:

A laser beam bounces off a series of mirrors

Explanation:

[tex]\text{Weight,}~ \\\\W = mg = 45 \times 9.8 = 441~ N\\\\\text{The weight of the object on earth is 441 N}.[/tex]

The spring constant of the spring if it would compress by 1 m to stop the ore car is 340,350.4 N/m.

The potential energy of the car is calculated as follows;

P.E = mgh

where;

sin (10) = h/L

h = L x sin(10)

P.E = mgLsin(10)

P.E = 2000 x 9.8 x 50 x sin(10)

P.E = 170,175.21

The potential energy of the car at the top of the incline will be converted  to the elastic potential energy spring at the bottom of the incline.

P.E = U = ¹/₂kx²

k = (2U)/x²

k = (2 x 170,175.2)/(1)²

k = 340,350.4 N/m

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Explanation:

s = ?           u = 0m/s        v = ?         a = 5m/s²        t = 2s

v = u + at                  

  = 0 + (5 x 2)              

  = 10 m/s                    

s = ut + 1/2 at²

= (0)(2) +  x    [tex]\frac{1}{2}[/tex]  x 5 x 2²

= 10 m

Hope this helps!

Answer:

visible waves are needed for green plants to grow.

Explanation:

During photosynthesis, chlorophyll absorbs energy from blue- and red-light waves, and reflects green-light waves, making the plant appear green.

Answer: Type I Error

Answer:

False

Explanation:

Scientific models are not always built to scale and may not be fully accurate

Answer:

The triboelectric effect is an electrical phenomenon where certain materials become electrically charged after coming into contact with another, different, material. The polarity and strength of the charges produced differ according to material and surface smoothness.

Explanation:

The triboelectric effect causes an electrostatic charge to build up on the fur due to the cat's motions. The electric field of the charges results in a slight attraction of the light plastic pieces to the charged fur. The triboelectric effect is also the cause of static cling in clothes.

I hope this helps, if it doesn't then just message me and ill be more than happy to help :)

The velocity of the mass after the force has stopped acting is 14 m/s.

The velocity of an object is the speed at which the object is moving in a specified direction.

Momentum is related to velocity and mass by the formula:

The velocity of the mass after 8 seconds is first determined.

Change in linear momentum = (1/2 × 2 × 6) + (6 × 4) + (1/3 ×2 × 6) = 36 kgm/s

Initial momentum = 18 kg × 12 m/s = 216 kgm/s

Final momentum = 216 + 36 = 252 kgm/s

Final Velocity = final momentum/mass

Velocity = 252/18 = 14 m/s

After 8 seconds, the force stops acting.

Therefore, the velocity of the mass after the force has stopped acting is 14 m/s.

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The decrease in kinetic energy during collision is 0.171 joule. Hence, option (D) is correct.

The energy an object has as a result of motion is known as kinetic energy in physics. It is described as the effort required to move a mass-determined body from rest to the indicated velocity.

The body holds onto the kinetic energy it acquired during its acceleration until its speed changes. The body exerts the same amount of effort when slowing down from its current pace to a condition of rest.

Hence, the decrease in kinetic energy during collision =

Total initial kinetic energy - total final kinetic energy

= {1/2 × 1.15 ×(1.05)² + 1/2 ×2.25 × 0² - (1/2 × 1.15 × 0.13² + 1/2 ×1.25 × 0.85²)} Joule

= { 0.633 + 0 - 0.010 - 0.452} joule

= 0.171 joule.

Hence, The decrease in kinetic energy during collision is 0.171 joule.

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The statement true about the analog signal is they can capture the entire sound wave when a song is recorded on a vinyl record, resulting in a Fuller and more accurate representation of the original song.

The analog signals are discrete in nature.

Sound can be recorded, stored and played by the use of either digital or analog techniques.

Vinyl records produces a continuous sound wave vs CDs. So, analog is more accurate,

Thus, correct option is 1.

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The statement indicating that 'Gravitation always does negative work' is FALSE.

Gravitation is a fundamental physical force that makes objects attract each other in the Universe.

This force (Gravitation) is required to maintain both constant positions and movement of objects.

In conclusion, the statement indicating that 'Gravitation always does negative work' is FALSE.

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Answer:false

Explanation:

Answer:

B. The law of conservation of energy

Explanation:

The law of conservation of energy states that energy can neither be created or destroyed which means that a perpetual motion machine, which creates its own power and energy, cannot be true since energy cannot be created.

Answer:

throwing a ball

Explanation:

because when we throw the ball we apply force so that the ball goes faster

Answer:

Ultrasound imaging (sonography) uses high-frequency sound waves to view inside the body.

Explanation:

Answer:

Just get searched then go back to class

Explanation: similar situation

The ratio v1/v2 of the speed of the comet at position 1 to the speed at position 2 will be the ratio of the angular velocity.

Comets are frozen leftovers from the formation of the solar system composed of dust, rock, and ices.

It should be noted that the tangential speed can alternatively be represented as;

[tex]\rm v_t= r\frac{d\theta}{dt}[/tex]

where,

θ  is the comet's position angle with respect to some given direction.

The amount dθ/dt is known as angular speed

The ratio v1/v2 of the speed of the comet at position 1 to the speed at position 2 IS;

[tex]\rm \frac{v_1}{v_2} = \frac{\frac{d \theta_1}{dt_1} }{\frac{d \theta_2}{dt_2} } \\\\\ \frac{v_1}{v_2} =\frac{\omega_1}{\omega_2}[/tex]

Hence,the ratio v1/v2 of the speed of the comet at position 1 to the speed at position 2 will be the ratio of the angular velocity.

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[tex]~~~~~~~F = mg\\\\\implies F = 0.2 \times 9.8\\\\\implies F = 1.96~N\\\\\text{The downward force is 1.96 N.}[/tex]

Answer:

ultraviolet radiation

The safest option in the lab if one need your vision to be corrected is  wear corrective glasses or lenses under your safety goggles for the whole experiment, but always check with your ta or instructor for your school's policy.

When someone is performing any project in the chemistry lab, he needs to be extra care taken by himself and and the most importantly from the school. The safety goggles are used to protect the eyes from any spiling off the chemical.

One should wear corrective glasses under the safety goggles during the whole experiment.

Thus, wear corrective glasses under the safety goggles during the whole experiment.

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Whenever the circuit is turned on, each of these elements has the same current through it. The correct option is A.

The current is stream of charges flowing through circuit from the positive terminal to the negative terminal of the voltage source.

A series circuit consists of a switch, a 6-v battery, a lightbulb, and some copper wire. The circuit has the current I flowing in it.  Light bulb will act as resistor. When the circuit is on, current will flow through the entire circuit and its elements starting from the positive terminal of battery to the negative terminal of battery.

Thus, whenever the circuit is turned on, each of these elements has the same current through it. The correct option is A.

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The procedure is not found here but a chemical reaction is characterized to be a process where substances are converted into products.

A chemical reaction is a process where one or more reactants are converted into chemical products.

In a chemical reaction, enzymes are molecules that speed up the process by lowering its activation energy.

In conclusion, the procedure is not found here but a chemical reaction is characterized to be a process where substances are converted into products.

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Answer:

100 m / s^

F =ma from this divided F and ma by m to get acceleration

a = F / m

a = ?

F = 5 N

m = 50 g = 0. 0 5 kg ; if 1 kg = 1000g how much kg of 50 g by criss cross method we get 0.05 kg

so; 5N / 0. 05 kg = 5kg m / s^ / 0.05 kg

kg cancel by kg

the result is 100 m/ s^

Answer:

I don't know.

Explanation:

I have no idea what you are referring to.

The solar system is smaller than a galaxy. Galaxies are composed of solar systems. The solar system is composed of planets revolving around a star (such as our sun). To put into perspective, there are about hundreds of billions of stars in our galaxy (the milky way). On the other hand, billions of galaxies make up the universe.

The speed of light is constant which is 299 792 458 m / s. The time is taken for light to reach an object can be used to measure the distance between objects in space. This is done by multiplying the time by the speed of light.

Distance in space is so vast and therefore impractical to use the basic SI units of meters and kilometers we use here on earth. Therefore the use of astronomical units and light years is used. Light years is the distance that light can cover in a year in the vacuum of space, while astronomical units is the distance between solar systems.

From the principle of energy conservation, the kinetic energy of the pendulum at 0.5 m is 14.7 J.

A pendulum swings back and forth and can be used to show the change of potential energy to kinetic energy and vice versa.

Given that the kinetic energy is converted to the potential energy; the potential energy at 0.5 m is 3 * 9.8 * 0.5 = 14.7 J.

Following the principle of energy conservation, the kinetic energy of the pendulum at 0.5 m is 14.7 J.

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The second diver have to leap to make a competitive splash by 4.08 m high.

The energy by virtue of its position is called the potential energy.

PE = mgh

where, g = 9.81 m/s²

Given is the diver jumps from a 3.00-m platform. one diver has a mass of 136 kg and simply steps off the platform. another diver has a mass of 100 kg and leaps upward from the platform.

The potential energy of the first diver must be equal to the second diver.

P.E₁ = P.E₂

m₁gh₁ = m₂gh₂

Substitute the vales, we have

136 x 3  = 100 x h₂

h₂ = ₂4.08 m

Thus, the second diver need to leap by 4.08 m high.

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