When Bob needs to send Alice a message with a digital signature, whose private key is used to encrypt the hash?

If you know that the universe is estimated to be 14 billion years old . what is the age of the universe in seconds ???? (knowing

Svetlanka [38]

Answer:

The estimated age of the universe is $4.42*10^{17}\ seconds$

Explanation:

Time Units Conversion

Sometimes we need to express magnitudes in different units, depending on the specific situation handled in the question or problem at hand. Magnitudes like length, time, mass, temperature, pressure, etc., can be expressed in several different units.

The most common units for time are years, months, days, hours, minutes, and seconds. There are 3,600 seconds in one hour and 24 hours in one day.

We are given the estimated age of the universe as 14 billion solar years. If one solar year is 365.25 days long, then the age, expressed in days is

14,000,000,000 * 365.25 days

Some quantities need to be expressed in scientific notation. This is the case since the numbers are too high

$14,000,000,000 * 365.25 = 5.1135*10^{12}\ days$

There are 24*3600=86400 seconds in one day, so

$5.1135*10^{12}\ days=5.1135*10^{12} * 86400 =4.42*10^{17}\ seconds$

The estimated age of the universe is $4.42*10^{17}\ seconds$

6 0

3 years ago

Read 2 more answers

Light striking a metal surface causes electrons to be emitted from the metal via the photoelectric effect.In a particular experi

ANEK [815]

The number of electrons emitted from the metal per second increases if the intensity of the incident light is increased.

Answer: Option B

Explanation:

As a result of photoelectric effect, electrons are emitted by the light incident on a metal surface. The emitted electrons count and its kinetic energy can measure as the function of light intensity and frequency. Like physicists, at the 20th century beginning, it should be expected that the light wave's energy (its intensity) will be transformed into the kinetic energy of emitted electrons.

In addition, the electrons count emitting from metal must vary with light wave frequency. This frequency relationship was expected because the electric field oscillates due to the light wave and the metal electrons react to different frequencies. In other words, the number of electrons emitted was expected to be frequency dependent and their kinetic energy should be dependent on the intensity (constant wavelength) of light.

Thus, the maximum in kinetic energy of electrons emitted increases with increase in light's frequency and is experimentally independent of light intensity. So, the number of emitted electrons is proportionate to the intensity of the incident light.

5 0

3 years ago

The earth and the moon exert forces on each other which forces is greater? explain

Helen [10]

Thank you for your question, what you say is true, the gravitational force exerted by the Earth on the Moon has to be equal to the centripetal force.

An interesting application of this principle is that it allows you to determine a relation between the period of an orbit and its size. Let us assume for simplicity the Moon's orbit as circular (it is not, but this is a good approximation for our purposes).

The gravitational acceleration that the Moon experience due to the gravitational attraction from the Earth is given by:

ag=G(MEarth+MMoon)/r2

Where G is the gravitational constant, M stands for mass, and r is the radius of the orbit. The centripetal acceleration is given by:

acentr=(4 pi2 r)/T2

Where T is the period. Since the two accelerations have to be equal, we obtain:

(4 pi2 r) /T2=G(MEarth+MMoon)/r2

Which implies:

r3/T2=G(MEarth+MMoon)/4 pi2=const.

This is the so-called third Kepler law, that states that the cube of the radius of the orbit is proportional to the square of the period.

This has interesting applications. In the Solar System, for example, if you know the period and the radius of one planet orbit, by knowing another planet's period you can determine its orbit radius. I hope that this answers your question.

8 0

3 years ago

Big Ben, a large artifact in England, has a mass of 1x10^8 kilograms and the Empire State Building 1x10^9 kilograms. The distanc

TiliK225 [7]

Answer:

The force, exerted by Big Ben on the Empire State Building is 2.66972 × 10⁻⁷ N

Explanation:

The question relates to the force of gravity experienced between two bodies

The given parameters are;

The mass of Big Ben, M₁ = 1 × 10⁸ kg

The mass of the Empire State Building, M₂ = 1 × 10⁹ kg

The distance between the two Big Ben and the Empire State Building, r = 5,000,000 meters

By Newton's Law of gravitation, we have;

$F=G \times \dfrac{M_{1} \times M_{2}}{r^{2}}$

Where;

F = The force exerted by Big Ben on the Empire State Building and vice versa

G = The universal gravitational constant = 6.67430 × 10⁻¹¹ N·m²/kg²

M₁, M₂, and r are the given parameters

By plugging in the values of the parameters and the constant into the equation for Newton's Law of gravitation, we have;

$F=6.67430 \times 10^{-11} \times \dfrac{1 \times 10^8 \times 1 \times 10^9}{(5,000,000)^{2}} = 2.66972 \times 10^{-7}$

The force, 'F', exerted by Big Ben on the Empire State Building is F = 2.66972 × 10⁻⁷ N.

3 0

3 years ago

The texture of obsidian is best described as glassy.Why does obsidian contain few or no mineral grains? by the way I put it unde

Brrunno [24]

hi, so the material that would normally form mineral crystals does not have time to form a crystalline structure because of very rapid cooling after volcanically erupting into the air or onto the surface. Obsidian is a volcanic glass.

4 0

3 years ago