How is one second time defined in SI system?​

Answers

Answer 1

Answer:

The second is defined in terms of a cesium-atom laser and its vibrations.

Explanation:

However, real time is defined in terms of the mean solar day, and it is thus necessary to add leap seconds to the atomic clocks to keep them in line with the astronomical clocks.

Hope this helped :)


Related Questions

A 0.10 newton spring toy with a spring constant of 160 newtons per meter is compressed 0.05 meter before it is launched. When released the spring toy pops up and reaches a maximum height of 1.5 meters.

1) How much elastic potential energy is initially stored in the spring?


2)How much internal energy is produced as the toy springs up to its maximum height?

Answers

Answer:

(1) V = 0.2 J (2) 0.05J

Explanation:

Solution

Given that:

K = 160 N/m

x = 0.05 m

Now,

(1) we solve for the  initial potential energy stored

Thus,

V = 1/2 kx² = 0.5 * 160 * (0.05)²

Therefore V = 0.2 J

(2)Now, we solve for how much of the internal energy is produced as the toy springs up to its maximum height.

By using the energy conversion, we have the following

ΔV = mgh

=(0.1/9.8) * 9.8 * 1.5 = 0.15J

The internal energy = 0.2 -0.15

=0.05J

Which statement below best describes the relationship between the voltage, resistance, and current?
Group of answer choices

A.) As voltage increases, current increases and resistance stays the same

B.) As voltage decreases, current and resistance stay the same

C.) As voltage decreases, current and resistance both increase

D.) As voltage increases, current and resistance both decrease

Answers

Answer:

As voltage increases, current increases and resistance stays the same .

Explanation:

Ohm's law gives the relationship between the voltage, resistance, and current. The mathematical form of Ohm's law is given by :

[tex]V\propto I\\\\V=IR[/tex]

R is resistance

I is current

V is voltage

So, as voltage increases, current increases and resistance stays the same. The correct option is (A).

Un tren de pasajeros viaja a razon de 36km/hrs al ingresar a un tunel de 200m de longitud demora 50seg en salir de el .¿cuanto es la longitud del tren?

Answers

Answer:

[tex]\Delta L = 300\,m[/tex]

Explanation:

La longitud del tren se deriva de la siguiente fórmula (The length of the train is derived from the following formula):

[tex]\Delta L + 200\,m = v\cdot \Delta t[/tex]

[tex]\Delta L = \left(36\,\frac{km}{h} \right)\cdot \left(1000\,\frac{m}{km} \right)\cdot \left(\frac{1}{3600}\,\frac{h}{s} \right)\cdot (50\,s) - 200\,m[/tex]

La longitud del tren es (The length of the train is):

[tex]\Delta L = 300\,m[/tex]

What is a lunar month

Answers

Answer:

It's the duration between successive new moons. Also called a lunation or synodic month, it has a mean period of 29.53059 days (29 days 12 hours and 44 minutes).

The adjective lunar is used to describe something that is related to the Moon.

If a 0.5 kg ball is thrown up with 250 J of kinetic energy, how high will it go?
(HINT: At the ball's highest point it has stopped.)
KE = 1/2mv2
G = 9.8 m/s2

Answers

Answer:

51.02m

Explanation:

KE = 1/2mv2

Where k.e = 250J

mass = 0.5 kg

g = 9.8 m/s2

250= 1/2×0.5×v^2

250= 0.5×0.5×v^2

250= 0.25v^2

v^2 = 250/0.25

v^2 = 1000

v =√1000

v = 31.62m/s

v^2= u^2-2gh........... (1)

Since the object will stop at it highest point, hence it final velocity there will be zero and since it is moving up against the gravity g= -9.8m/s^2. That was why the formula in equation 1 has a negative sign

From h = u^2/2g

Where v = 31.62m/s

g = 9.8m/s^2

H = (31.62m/s)^2/9.8×2

H= 1000/19.6

= 51.02m

Hence the height of it travelling will be

51.02m

A small object begins a free-fall from a height of =81.5 m at 0=0 s . After τ=2.20 s , a second small object is launched vertically up from the ground with an initial velocity of 0=40.0 m/s . At what height from the ground will the two objects first meet?

Answers

Answer:

33.23 m

Explanation:

At the point where both objects will meet, the vertical height will be equal.

From the equations of motion, the vertical height of the body falling at any time is given as

(y - y₀) = ut + ½gt²

y = vertical height at any time T

y₀ = initial height of the object = 81.5 m

u = initial velocity = 0 m/s (body was dropped)

g = -9.8 m/s²

(y - 81.5) = 0 - 4.9T²

y = 81.5 - 4.9T² (eqn 1)

For an object thrown up, the vertical height of the body at any time, t, is given as

(y - y₀) = ut + ½gt²

y = vertical height of the object at any time t

y₀ = initial height of the object = 0 m

u = initial velocity = 40 m/s

g = -9.8 m/s²

y = 40t - 4.9t² (eqn 2)

At the point where the two objects meet, we equate eqn 1 and eqn 2

y = y

81.5 - 4.9T² = 40t - 4.9t²

But T = (t + 2.2) (Since object 2 was dropped 2.2 s after object 1)

81.5 - 4.9(t + 2.2)² = 40t - 4.9t²

81.5 - 4.9(t² + 4.4t + 4.84) = 40t - 4.9t²

81.5 - 4.9t² - 21.56t - 23.716 = 40t - 4.9t²

81.5 - 21.56t - 23.716 - 40t = 0

57.784 = 61.56t

t = (57.784/61.56) = 0.93866 = 0.94 s

Therefore, the vertical height at t = 0.93866 s is

y = (40×0.93866) - 4.9(0.93866²) = 33.23 m

Hope this Helps!!!

The speed of light in a material is 0.50


c. what is the critical angle of a light ray at the interface between the material and a vacuum?

Answers

Answer:

Explanation:

This problem indicates that the speed of light in a material medium is 0.5 10⁸ m / s, they ask to find the critical angle between the material and the vacuum

Let's find the refractive index of the material

            n = c / v

           n = 3 10⁸ / 0.5 10⁸

           n = 6

When the material passes from one medium to another, it must comply with the law of refraction

           n₁ sin θ = n₂ sin θ₂

for the angle criticize the angles tea2 = 90

          tea = sin⁻¹n₂/ n₁

The vacuum replacement index is n₂ = 1

         tea = sin⁻¹ (1/6)

         tea = 9.59º

Answer:

30 degrees

Explanation: First, what is the critical angle? Critical angle is the angle from the normal, at which light enters another medium, which causes the reflected light to reflect at an angle of 90 degrees.

Using Snell's Law:

critical angle = sin^-1(n2/n1)

n2 = c/v. In a vacuum this = 1

n1 = c/.5c = 2

critical angle = sin^-1(1/2)=30 degrees

A car with a crashtest dummy inside travels at 40.23 m/s (90 mph) toward a stone wall during a crash test. When it strikes the wall, the car takes 0.70 s to stop. Calculate the deceleration of the car.

Answers

Answer:

The answer is  [tex]-57.47m/s^{2}[/tex]

Explanation:

In the question we are  to solve for the deceleration  of the car on impact.

Given data

[tex]speed= 40.23m/s\\[/tex]

[tex]time[/tex] =[tex]0.70second[/tex]

To determine the deceleration  we apply,

[tex]acceleration = \frac{speed}{time} \\\\acceleration= \frac{40.23}{0.7}[/tex]

[tex]acceleration = -57.47m/s^{2}[/tex]

Where is earth's magnetic north pole located?

Answers

Answer: it is located over Ellesmere Island, Canada

Explanation

it is now drifting away from North America and toward Siberia.

Answer:ellesmere island, Canada

Question 2
A wave with a frequency of 10 Hz and a wavelength of 4 m would have what speed?
m/s

Answers

Answer:

speed = 40 m/s

Explanation:

speed = frequency x wavelength

speed = 10 Hz x 4 m

speed = 40 m/s

A concave mirror has a radius of curvature of 0.60 meter.
When an object is placed 0.40 meter from the reflecting
surface, the image distance will be
0.10 m
0.20 m
0.83 m
o 1.2 m

Answers

pls give me brainliest!!!

what is electrostatic force all about?​

Answers

Explanation:

the electrostatic force is also known as the coulomb force or coulomb interaction. it's the attractive or repulsive force between two electrically charged object. like charges repel each other while unlike charges attract each other. coulomb's law is used to calculate the strength of the force between two charger .

A point charge (5.0 pC) is located at the center of a spherical surface (radius = 2.0 cm), and a charge of 3.0 pC is spread uniformly upon this surface. Determine the magnitude of the electric field 1.0 cm from the point charge.

Answers

Answer:

E = 0.45 kN/C

Explanation:

From; the question, we can opine that the electric field inside the hollow sphere as a result of the  charge at the surface is zero.

Using the equation:

[tex]\mathbf{E = kq/r^2}[/tex]  to determine the magnitude of the electric field with the radius 1.0 cm from the point charge.

where ;

constant k = [tex]8.98*10^9[/tex]

point charge  q = 5.0 pC = 5.0 × 10⁻¹²; we have :

[tex]\mathbf{E = kq/r^2}[/tex]

[tex]\mathbf{E =\dfrac{8.98*10^9*5*10^{-12}}{1.0^2}}[/tex]

E = 0.45 kN/C

If a car accelerates uniformly from rest to 15 meters
per second over a distance of 100 meters, the magnitude of the car’s acceleration is

Answers

Answer:

1.125 m/s²

Explanation:

Applying Newton's equation of motion,

v² = u²+2as

Where v = final velocity, u = initial velocity, a = acceleration, s = distance.

Note: u = 0 m/s ( from rest)

make a the subject of the equation above.

a = v²/2s................ Equation 2

Given: v = 15 m/s². s =  100 m

Substitute into equation 2

a = 15²/(2×100)

a = 225/200

a = 1.125 m/s²

The magnitude of the car's acceleration is 1.125 m/s²

The calculation can be as follows;

u= 0

v= 15m/s

s= 100 meters

The formular is

v²= u² + 2as

15² = 0² + 2(a)(100)

225= 200a

a= 225/200

a= 1.125

Hence the initial velocity is 1.125 m/s²

Please see the link below for more information

https://brainly.com/question/6078363?referrer=searchResults

The RMS potential difference of an AC household outlet is 117 V. a) What is the maximum potential difference across a lamp connected to the outlet? b) If the RMS current through the lamp is 5.5 A, what is the lam

Answers

Answer:

a. 165.5 V

b. 7.78 A

Explanation:

Here is the complete question

The RMS potential difference of an AC household outlet is 117 V. a) What is the maximum potential difference across a lamp connected to the outlet? b) If the RMS current through the lamp is 5.5 A, what is the maximun current through the lamp.

Solution

a. The maximum potential difference across the lamp V₀ = √2V₁ where V₁ = rms value of potential difference = 117 V

V₀ = √2V₁ = √2 × 117 V = 165.5 V

b. The maximum current through the lamp I₀ = √2I₁ where I₁ = rms value of current = 5.5 A

V₀ = √2V₁ = √2 × 5.5 A = 7.78 A

You are pushing a box up a ramp with 70 N of force. If the ramp is made steeper and shorter, what needs to happen to the box for it to continue moving?

Answers

Answer:

A larger force than 70 N will be required for the box to continue moving

Explanation:

A ramp is an inclined plane surface that is tilted to form a slope on its opposite sides

A ramp provides mechanical advantage or force amplification, by allowing less force to lift heavier load from having to move through a longer distance to reach a particular elevation when the slope of the ramp is gentle

Therefore, when the slope is steeper, and shorter, more force than 70 N will be required for the box to continue moving.

Answer:  

your force needs to increase to more than 70 N

Explanation:

plato

i really need help !!

Answers

Answer:

The generator will work only if the magnetic field associated with the turns of coil change.

here both magnet and coil are stationary with respect to each other so no electromagnetic induction would take place. so no indiced current will be produced.

the student has to introduce some mechanism either to rotate the coil or the magnet

El tiempo de reacción de un conductor de automóvil es 0,75s. Si el automóvil puede experimentar una desaceleracion de 4m/s^2. Calcular la distancia recorrida hasta detenerse una vez recibida la señal, cuando su velocidad era 10m/s

Answers

Answer:

x_total = 20m

Explanation:

This is an exercise in kinematics, we will look for the distance it travels during the reaction time, where there is no braking, and then the distance during the deceleration.

Distance traveled during response time

           v = x₁ / t

           x₁ = v t

let's calculate

          x₁ = 10 0.75

          x₁ = 7.5 m

Now we calculate the distance during braking, the final speed is zero (v = 0)

         v² = v₀² - 2 a x₂

         x₂ = v₀² / 2 a

let's calculate

         x₂ = 10² / (2 4)

         x₂ = 12.5m

the total stopping distance is

        x_total = x₁ + x₂

        X_total = 7.5 + 12.5

        x_total = 20m

El piloto de un contenedor parte de la ciudad de Guatemala a las 8:00 AM hacia Puerto Barrios, Izabal, debiendo recorrer 310 km sobre la carretera hasta llegar a la entrada del puerto donde debe entregar el contenedor a las 12:00 del mediodía. Calcule la rapidez promedio a la que deberá conducir el piloto para poderlo entregar a tiempo. Si el piloto sabe de antemano que debe detenerse una hora para hacer cola en el Progreso, por la ampliación de la carretera, calcule cuál debería ser entonces la rapidez promedio a la que debe conducir. ¿Medite si será posible o razonable que un contenedor viaje por la carretera a esa rapidez? Si la distancia en línea recta desde la ciudad de Guatemala hasta Puerto Barrios es de 250 km. ¿Cuál es la longitud de la trayectoria del contenedor? ¿Cuál fue su desplazamiento?

Answers

Sorry I don’t understand so I can’t help

what should police remove to study the physical conditions of a gun homicide case?


the victims clothes


any valuables from the victim (wallet, jewelry)


the victims cell phone


the victims dentures, if they wear any

Answers

Answer:

Explanation:

the victims cell phone

Calculate the efficiency of an engine if the work input is 300. J and the work output is 100. J

Answers

Answer:

33.33%

Explanation:

take efficiency =power output/power input multiply by 100%

Problem
When a piece of aluminum is
placed in a 25 ml
graduated
cylinder that contains 10.5mL of water, the water level rises to 13.5m. What is the mass of
the aluminum?​

Answers

boy shut up i have no time for this and i feel like it’s non sense so yea put what you feel it correct

Why can chemical energy and nuclear energy be considered a potential energy

Answers

Answer:

because it is due the Intrecation between sub atomic particles

PLEASE HELP WILL GIVE BRANLIEST, EXTRA POINTS!

Jailah needs a replacement for lithium for a science experiment. She tries silicon, but it does not work. Using what you know about patterns in the periodic table, which advice would you give Jailah?
A. Try a lanthanide series element.
B. Try a non-metal from the halogen group.
C. Try an element in the same group as lithium.
D. Try an element in the same period as lithium.

Answers

Answer:

C. Try an element in the same group as lithium.

Explanation:

Answer:

The answer is C.

Explanation:

I'm took the test on it

The space shuttle approaches earth at a speed of 2.89*10^4 km/h when it sends a radio signal to earth 1.00*10^5 km away. The radio signal will reach earth in ____ seconds

Answers

Answer:

3 secods later

Explanation:

How long will it take you to drive the 256 miles to get to the Mackinac Island Ferry if you average 70 mi/hr? If you leave at 3:00, what time will you get there? *Using speed formula

Answers

Answer:

If the speed is 70 mile/hour, the time to drive the 256 miles is:

T = 256/70 = 3.66 hours = 3 hours and 39.6 minutes

If you leave at 3:00, then at 6 hours and 39.6 minutes, you will get there.

Hope this helps!

:)

You're sitting on a warm granite rock, enjoying the sunshine. You decide it's time to test the water. You take off your shoes and walk across the cool sand to the water. You wade into the water, enough to cover your feet. Brrr! The water is cold. You will have to wear a dry suit when you go diving.
a. Which item - the granite rock, the sand, or the water - has the highest specific heat? Which has the lowest specific heat?
b. Which item requires the least energy to increase its temperature? Explain your answer in terms of this item's specific heat.
c. If the granite rock on which you were sitting has a specific heat of 600 J/(kg°C), how much energy must be added to a 2-kilogram piece of it to increase its temperature from 20°C to 30°C? Show your work, including the equation you need to perform this calculation.
d. What is the second law of thermodynamics? Use this law to describe why your feet got cold, not hot, when you put them in the water.

Answers

Answer: seen below

Explanation:

a) Water has the highest specific heat capacity in this case while sand has the lowest specific heat capacity.

b) Sand absorb the least energy for it temperature change (increase or decrease). This means that their temperatures change more quickly due to it low specific heat capacity of 0.290J/g°C) at 25°C)

c) using the formula:

Q = m × cP × (final temperature -initial temperature)

where:

Q = heat

m = is the mass

cP = is the mass heat capacity,

T= is the temperature

Q = 2 kg × 600 J/(kg°C) × (30°C - 20°C)

Q = 12000 J

d) in simpler term, The second law of thermodynamics states that when energy changes from one form to another form, entropy The second law of thermodynamics says that when energy changes from one form to another form, or matter moves freely, entropy (which is a measure of the amount of energy in a physical system that cannot be used to do work) in a closed system increases. This is why your feet gets cold when you put them in the water.

How do air quality scientists ensure the air is cleaned? What steps do they take?

Answers

Air sample of places around the world compared to clean air

You accidentally drop a book down a stairwell. Assuming no air resistance,
how fast will the book be moving after 0.75 seconds?​

Answers

Answer:

if we drop it and not throw it then

after 0.75 how fast the book is falling is given by its velocity as

v= at

= 9.8 × 0.75

=7.35 m/s

17.
What type of energy wave is highest in energy? (3 points)
Radio wave
Microwave
Visible light
Gamma wave

Answers

Answer:

gamma waves

Explanation:

gamma rays" from lightning discharges at 10 to 20 MeV, and known to be produced by the bremsstrahlung mechanism. Another example is gamma-ray bursts, now known to be produced from processes too powerful to involve simple collections of atoms undergoing radioactive decay.

Gamma waves should have the highest in energy
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