_______ says the universe began as a point and expanded. A. Evolution B. The Big Bang theory C. Cosmology D. Hubble's law

Alexis walked 1.5 km to her house in 0.5 hours. What is Alexis’ speed?

katrin2010 [14]

Answer:

Speed = 3 [km/h]

Explanation:

To solve this problem we must use the definition of speed which relates the distance traveled for a while.

Distance = 1.5 [km] = 1500 [m].

time = 0.5 [hr] = 1800 [s]

Speed = Distance/time

Speed = 1.5/0.5

Speed = 3 [km/h] or 1500/1800 = 0.8333[m/s]

4 0

2 years ago

Which law states that absolute zero cannot be reached?

Lera25 [3.4K]

Assuming you mean temperature

Answer: The third law of thermodynamics

6 0

2 years ago

A large helium filled balloon is used as the center piece for a graduation party. The balloon alone has a mass of 222 kg and it

inn [45]

Answer:

The buoyant force is 3778.8 N in upward.

Explanation:

Given that,

Mass of balloon = 222 Kg

Volume = 328 m³

Density of air = 1.20 kg/m³

Density of helium = 0.179 kg/m³

We need to calculate the buoyant force acting

Using formula of buoyant force

$F_{b}=\rho_{air}\times V_{b}\times g$

Where, $\rho_{air}$ = density of air

V = Volume of balloon

g = acceleration due to gravity

Put the value into the formula

$F_{b}=1.20\times321\times9.81$

$F_{b}=3778.8\ N$

This buoyant force is in upward direction.

Hence, The buoyant force is 3778.8 N in upward.

4 0

2 years ago

Consider a cyclotron in which a beam of particles of positive charge q and mass m is moving along a circular path restricted by

Ulleksa [173]

A) $v=\sqrt{\frac{2qV}{m}}$

B) $r=\frac{mv}{qB}$

C) $T=\frac{2\pi m}{qB}$

D) $\omega=\frac{qB}{m}$

E) $r=\frac{\sqrt{2mK}}{qB}$

Explanation:

A)

When the particle is accelerated by a potential difference V, the change (decrease) in electric potential energy of the particle is given by:

$\Delta U = qV$

where

q is the charge of the particle (positive)

On the other hand, the change (increase) in the kinetic energy of the particle is (assuming it starts from rest):

$\Delta K=\frac{1}{2}mv^2$

where

m is the mass of the particle

v is its final speed

According to the law of conservation of energy, the change (decrease) in electric potential energy is equal to the increase in kinetic energy, so:

$qV=\frac{1}{2}mv^2$

And solving for v, we find the speed v at which the particle enters the cyclotron:

$v=\sqrt{\frac{2qV}{m}}$

B)

When the particle enters the region of magnetic field in the cyclotron, the magnetic force acting on the particle (acting perpendicular to the motion of the particle) is

$F=qvB$

where B is the strength of the magnetic field.

This force acts as centripetal force, so we can write:

$F=m\frac{v^2}{r}$

where r is the radius of the orbit.

Since the two forces are equal, we can equate them:

$qvB=m\frac{v^2}{r}$

And solving for r, we find the radius of the orbit:

$r=\frac{mv}{qB}$ (1)

C)

The period of revolution of a particle in circular motion is the time taken by the particle to complete one revolution.

It can be calculated as the ratio between the length of the circumference ( $2\pi r$ ) and the velocity of the particle (v):

$T=\frac{2\pi r}{v}$ (2)

From eq.(1), we can rewrite the velocity of the particle as

$v=\frac{qBr}{m}$

Substituting into(2), we can rewrite the period of revolution of the particle as:

$T=\frac{2\pi r}{(\frac{qBr}{m})}=\frac{2\pi m}{qB}$

And we see that this period is indepedent on the velocity.

D)

The angular frequency of a particle in circular motion is related to the period by the formula

$\omega=\frac{2\pi}{T}$ (3)

where T is the period.

The period has been found in part C:

$T=\frac{2\pi m}{qB}$

Therefore, substituting into (3), we find an expression for the angular frequency of motion:

$\omega=\frac{2\pi}{(\frac{2\pi m}{qB})}=\frac{qB}{m}$

And we see that also the angular frequency does not depend on the velocity.

E)

For this part, we use again the relationship found in part B:

$v=\frac{qBr}{m}$

which can be rewritten as

$r=\frac{mv}{qB}$ (4)

The kinetic energy of the particle is written as

$K=\frac{1}{2}mv^2$

So, from this we can find another expression for the velocity:

$v=\sqrt{\frac{2K}{m}}$

And substitutin into (4), we find:

$r=\frac{\sqrt{2mK}}{qB}$

So, this is the radius of the cyclotron that we must have in order to accelerate the particles at a kinetic energy of K.

Note that for a cyclotron, the acceleration of the particles is achevied in the gap between the dees, where an electric field is applied (in fact, the magnetic field does zero work on the particle, so it does not provide acceleration).

6 0

3 years ago

The Dark Matter Halo of our galaxy is The Dark Matter Halo of our galaxy is a halo component curiously absent in most others gal

erma4kov [3.2K]

Answer:

you mean this halo right

Explanation:

Halo is an American military science fiction media franchise managed and developed by 343 Industries and published by Xbox Game Studios. The franchise and its early main installments were originally developed by Bungie. The central focus of the franchise builds off the experiences of Master Chief John-117, one of a group of supersoldiers codenamed Spartans, and his artificial intelligence (AI) companion, Cortana.

The original trilogy centers on an interstellar war between humanity and an alliance of aliens known as the Covenant. The Covenant, led by their religious leaders called the Prophets, worship an ancient civilization known as the Forerunners, who perished while defeating the parasitic Flood. The eponymous Halo Array are a group of immense, habitable, ring-shaped superweapons that were created by the Forerunners to destroy the Flood, but which the Covenant mistake for religious artifacts that, if activated, would transport them on a Great Journey to meet the Forerunners. They are similar to the Orbitals in Iain M. Banks' Culture novels, and to a lesser degree to author Larry Niven's Ringworld concept.[1][2][3][4]

The games in the series are critically acclaimed, with the original considered the Xbox's "killer app".[5] This led to the term "Halo killer" being used to describe console games that aspire, or are considered, to be better than Halo.[6] Fueled by the success of Halo: Combat Evolved, and by marketing campaigns from publisher Microsoft, its sequels went on to record-breaking sales.[7][8][9] The games have sold over 65 million copies worldwide, with the games alone grossing almost $3.4 billion.[10][11][12] Halo has since become one of the highest-grossing media franchises of all time. These strong sales led to the franchise's expansion to other media; the Halo Universe now spans multiple best-selling novels, graphic novels, comic books, short movies, animated movies and feature films, as well as other licensed products.

T

6 0

3 years ago