what is the best defintion of efficency

Answer:

Reproducible by other scientists

Explanation:

I just took the test

Answer: "Surface tension is a film of a liquid caused by the attraction of the particles in the surface layer by the bulk of the liquid, which tends to minimize surface area."

Hope this helps!

Answer:

Explanation:

Surface tension is the property of a liquid surface. It is an effect where the surface of the liquid is strong.

example - small insects can walk on water as they do not have enough weight to penetrate it.

This image might help you

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Answer:

  #_total = 4.38 10⁹ liter

Explanation:

For this exercise we can use a direct proportion rule (rule of three). If 4 people use 1200 liters how much water 1 person consumes

            #_water = 1 person (1200 liter / 4 person)

            #water = 300 liters

Now we look for the consumption of this person in a year, if 1 person consumes 300 liters 1 day, how many liters they consume in a year (365 days)

           #_water_person_total = 365 days (300 liters / 1 day)

           #_water_person_total = 109500 liters

This is the water consumption of 1 person in a year, the total of 40000 people how much they consume

           #_total = 40000 person (109500 liter / 1 person)

           #_total = 4.38 10⁹ liter

Answer:

Pressure

Explanation:

One of the theories propounded by the Kinetic molecular theory, and which also provides an explanation of the several gas laws, is the statement that the gas molecules in a container, travel in straight lines and are in constant collision with themselves and the walls of the container, thus exerting force. This force is the pressure which is defined as the force per unit area.

There is no loss of energy in the collisions involving the gas molecules and that is why their movement can be described as elastic. The descriptions of the behavior of gas molecules in the Kinetic Molecular Theory, give rise to Charles law, Boyle's Law, Avogadro's Laws, Dalton's Law, and Amonton's Law.

Answer:

The pressure

Explanation:

Molecules of gases are constantly in motion, colliding with the walls of their container. This constant collision impacts force on the walls of the container, which depends on the speed with which the molecules are moving. The speed with which these molecules travel depends on the average kinetic energy of the molecules, which is proportional to the temperature.

This force when exerted per unit area is the pressure the gases exert on the walls of the container.

Answer:

1 Watt

Explanation:

Power (P) = w / Δt

w = work done

Δt = change in time

Power (P) = 60kg / 60 seconds

Power (P) = 1 Watt

Answer:

B. 0.2 J/g/°C

Explanation:

The solid phase is the first segment (from 0°C to 50°C).

q = mCΔT

200 J = (20 g) C (50°C)

C = 0.2 J/g/°C

Answer: √(L/g)

Explanation:

Here we only work with the units:

The unit of the period is units of time, so we have:

[T] = [s]

Now, the units of the length of the pendulum are units of distance:

[L] = [m]

And the units of the acceleration are:

[g] = [m/s^2]

Now, we want to work with those two in such way that the end result is only in seconds.

First, we can see that in g we have seconds square, so we know that we should use a square root.

Then we can divide L by g in order to remove the distance unit, and to have the time unit in the numerator

[L/g] = [m*s^2/m] = [s^2]

Now we apply the square root:

[√(L/g)] = [√s^2] = [s]

Then the combination is: √(L/g)

T = k*√(L/g)

where k is the constant of proportionality.

Answer:

In what way is iron unique among the elements?

It has the lowest mass per nuclear particle.

Match words at the left to the correct blanks in the sentences on the right. Not all words will be used.

-The energy that drives the expansion of a star into a subgiant or red giant comes from HYDROGEN SHELL FUSION

-Stars with mass greater than about 8 solar masses are considered HIGH-MASS STARS

-The final stage of core fusion in a low-mass star is HELIUM FUSION

-Stars that are fusing hydrogen in their cores are MAIN-SEQUENCE STARS

-When it dies, a high-mass star explodes as a SUPERNOVA

-A star that is expanding (into a subgiant and then a giant) has a(n) INERT HELIUM CORE

-When it dies, a low-mass star expels a PLANETARY NEBULA

-Stars with masses less than about two solar masses are considered LOW-MASS STARS

Answer:

Explanation:

The weight of a body is defined as the force with which it is attracted towards the centre of a planet. A spring balance measures it. It's unit is Newton ( N ) in the SI system and dyne in the CGS system.

Hope I helped!

Best regards!

Weight is force.

The CGS unit of force is the dyne.

The SI unit of force is the Newton.

Explanation:

a) Acceleration is the slope of the velocity vs time graph.  When velocity vs time is a straight line, that means the acceleration is a constant.  F = ma, so the resultant force is also constant.

b) As air resistance increases, the acceleration begins to decrease.

c) A falling object stops accelerating when it reaches terminal velocity.

d) F = ma, so when the acceleration is 0, the resultant force is also 0.

Explanation:

Hi,

The answer is friction.

There is almost no machine which are not affected by friction. It losts some work due to friction while working.

Hope it helps..

Answer:

friction

Explanation:

the other options dont effect efficiency

Answer:

a)  T = 1.26 s , b)  v_max = 0.14 m / s ,  a_max = 0.7 m / s²

c) x = 0.028 cos (5 t) ,    v = - 0.14 sin 5t,   a = - 0.7 cos 5t

Explanation:

This is a simple harmonic motion exercise that is described by the equation

    x = A cos (wt +Ф)

with

          w = √ (k / m)

let's apply this expression to our case

a) Angular velocity is related to frequency

          w = 2π f

frequency and period are related

          f = 1 / T

we substitute

         2π / T = √ (k / m)

         T = 2π √(m / k)

let's calculate

         T = 2π √(1/25)

          T = 1.26 s

In the expression for the period, the amplitude does not appear, therefore there is no dependence, as long as Hooke's law is fulfilled, which is correct for small amplitudes.

b) in the initial equation we have the position as a function of time, let's use the definition of speed and acceleration

           v = dx / dt

           v = - A w sin (wt + Ф)

the speed is maximum when the sine is -1

            v_max = A w

            w = √ (k / m)

            w = √ 25/1

            w = 5 rad / s

the amplitude of the movement is equal to the maximum compression of the spring

            A = 2.8 cm = 0.028 m

we substitute

            v_max = 0.028 5

            v_max = 0.14 m / s

acceleration

             a = dv / dt

             a = - A w² cos (wt + Ф)

the acceleration is maximum when the cosine is -1

             a_max = A w²

let's calculate

             a_max = 0.028 5²

             a_max = 0.7 m / s²

c) let's start by finding the phase constant

              v = -A w cos (wt + Ф)

at t = 0 they indicate that the system has v = 0

              0 = -A w sin (0 + Ф)

              Ф = sin⁻¹ 0

              Ф = 0

we write the equation

            x = 0.028 cos (5 t)

           v = - A w sin (wt + Ф)

           v = - 0.028 5 sin (5t + 0)

           v = - 0.14 sin 5t

acceleration

           a = - A w² cos (wt + Ф)

           a = - 0.028 5 2 cos (5 t + 0)

           a = - 0.7 cos 5t

Answer:

a business who buys goods and services

Answer:

D

Explanation:

because light has no space nor mass

Answer:

Parallel processing

Explanation:

It is a parallel processing because it involves the brain processing many part of problem simultaneously.

The brain natural mode of information involves performing many task .

It is also ability of the brain to simultaneously process incoming stimuli or signals of different quality. It is a part of brain's vision and divide what is seen into four major parts which are color, motion, shape, and depth.

Answer: B)  Parallel processing

Answer:

A person climbs a set of stairs

Explanation:

Potential energy is said to be possessed by an object due to its position. As the height from the ground level increase, the potential energy increases. It is calculated by the below formula as :

P = mgh

Out of the given options, the option that illustrates an increase in potential energy is option (b) i.e. a person climbs a set of stairs. As he steps one stair, its position from ground increases. It means its potential energy increases.

Answer:

C. Meter

Explanation:

The International System of Unit (SI) is gotten from the french word Systeme international is a modern form of metric measurement. It is the system of measurement that is universally accepted. It is from this SI units that all other system of units are derived. There are seven basic SI units which are:

1) Length in Meter (m)

2) Time in Seconds (s)

3) Amount of Substance in mole (m)

4) Electric current in ampere (A)

5) Temperature in kelvin (k)

6) Luminous intensity in candela (cd)

7) Mass in kilogram (kg)

Answer:

The atom is mostly empty space.

Explanation:

Ernest Rutherford in the year 1911 developed a model of an atom. In his model the atom was shown that the atom is mostly empty spaces composed of negative electrons which orbits round a positive nucleus just like planets revolving round the sun.

Rutherford came up with this model by performing experiments in 1909 which involves the scattering of alpha particles on a thin gold foil. From this experiments he came up with his model.

Answer:

A!

Explanation:

The atom is mostly empty space.

Answer:

I do not agree with the answer.

Because in reality, the atom has 2 main parts and 3 subatomic particles.

Explanation:

The parts of an atom are:

- The crust: It is the outer part of the atom and is the place where the electrons are.

- The nucleus: It is the central part of the atom and is the place that contains the protons and neutrons.

The subatomic particles of the atom are:

- Electrons: They are negatively charged particles that go in the atom's crust and are divided into specific sections.

- Protons: They are particles with a positive electric charge, the number of protons in the nucleus of an atom is what determines the atomic number of an element.

- Neutrons: They are atoms with no electric charge.

Explanation:

Hi, there!!

Energy is defined as the capacity or ability to do work. It's SI unit is Joule.

here,

Joule = (kg×m×m)/(s×s)

= kg×m^2/s^2.

Therefore, the derived unit is kg.m^2 by s^2.

Hope it helps...

Answer:

When we have irregular objects, it may become very hard to calculate the volume of the object, as we actually can not use any simple equation to find it.

The mass is less tricky, just find a scale and wheight it, now we know the mass of the irregular object.

One way to measure the volume of the object is using water... how we do it?

Get some recipient with water, measure the height of the water.

Introduce your object into the water and totally submerge it, now the level of the water will rise. This is because as you introduce the object under the water, you are displacing up a given volume of water that has the same volume as the irregular object.

Now that you know the height of the water before and after you put your object, you can easily calculate the volume of water displaced, and that will be the volume of the object (the tricky part may be totally submerging the object if, for example, is wood and it floats, here you can use a thin wire to push it down but it will affect a little bit the measures.)

Answer:

The mass of the object and its height in the gravitational field of the Earth.

Explanation:

If we are talking about gravitational potential energy which is defined as:

[tex]U=m\,*\,g\,*\,h[/tex]

being "m" the object's mass, "g" the acceleration due to gravity, and "h" the height at which the object is located relative to the conventionally picked level for zero of potential energy.

As long as the value of "g" is constant, the only two variables that determine the gravitational potential energy are the mass (m) of the object and its relative height (h).

Answer:

The objects weight and height above Earth's surface

Explanation:

K12 :)

Answer:

the final statements the correct one is. The second

The iron piece exerts a force of 1 N on the magnet in the opposite direction

Explanation:

In this exercise they give us the force exerted by a magnet on an iron bar and ask us the force that the iron bar exerts on the magnet. We can see that these are action and reaction forces, which by Newton's third law must be of equal magnitude and opposite direction, each applied to one of the bodies.

the final statements the correct one is. The second

The iron piece exerts a force of 1 N on the magnet in the opposite direction

Explanation:

The ratio of the areas is the square of the ratio of the radii.

A/A = 3.16² = 9.99

The ratio of the volumes is the cube of the ratio of the radii.

V/V = 3.16³ = 31.6

Ignoring the air resistance it will take about 3 seconds for the object to reach the ground.We know that the acceleration due to gravity is 10m/s2.

We also know that the final velocity is 30 m/s while the initial velocity is 0 m/s

we can use the formulae for acceleration to calculate the time taken/

(final - initial velocity)/timetaken=10

(30-0)/timetaken=10

timetaken =30/10=3 seconds

Answer:

230 = x + 105

x= 125

Explanation:

v = v0 + at

Answer:

Explanation:

On rubbing a glass rod with silk, the electrons from the glass rod get transferred to the silk. The silk now has an excess of electrons and so is negatively-charged. On the other hand, the glass rod is deficient in electrons and hence is positively-charged.

In the above case, the silk undergoes negative electrification.

Now, when the positively charged glass rod is touched on the disc of a negatively charged gold leaf electroscope, the electrons shifts towards rod, hence amount of charge on gold leaves decreases and the divergence between the gold leaves decreases as unlike charges attract each other.

Hence, the divergence decreases when a glass rod rubbed with silk is brought near the disc of negatively charged electroscope.

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Answer: ear phones

Explanation:

You can physically hold ear phones, but you can't hold music, sunlight, or heat.

Answer:

The correct option is;

a. 12.5 g

Explanation:

The given parameters are;

The initial mass of the radioactive substance = 200 g

The half life of the radioactive substance = 50 years

The time duration for the disintegration = 200 years

The formula for half life is given as follows;

[tex]N(t) = N_0 \left (\dfrac{1}{2} \right )^{\dfrac{t}{t_{1/2}}[/tex]

Where:

N(t) = Quantity of the remaining substance

N₀ = Initial radioactive substance quantity  = 200 g

t = Time duration  = 200 years

[tex]t_{1/2}[/tex] = Half life of the radioactive substance  50 years

Therefore, we have;

[tex]N(t) =200 \times \left (\dfrac{1}{2} \right )^{\dfrac{200}{50} } =200 \times \left (\dfrac{1}{2} \right )^4 = 12.5 \ g[/tex]

Therefore, at the end of 200 years, the quantity left = 12.5 g.