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3 years ago

If a quasar is moving away from us at v/c = 0.8, what is the measured redshift?

Physics

1 answer:

Delicious77 [7]3 years ago

4 0

Answer:

The measured redshift is z =2

Explanation:

Since the object is traveling near light speed, since v/c = 0.8, then we have to use a redshift formula for relativistic speeds.

$z= \sqrt{\cfrac{c+v}{c-v}}-1$

Finding the redshift.

We can prepare the formula by dividing by lightspeed inside the square root to both numerator and denominator to get

$z= \sqrt{\cfrac{1+\cfrac vc}{1-\cfrac vc}}-1$

Replacing the given information

$z= \sqrt{\cfrac{1+0.8}{1-0.8}}-1$

$z= \sqrt{\cfrac{1.8}{0.2}}-1\\z= \sqrt{9}}-1\\z=3-1\\z=2$

Thus the measured redshift is z = 2.

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The top of a swimming pool is at ground level. If the pool is 3.00 m deep, how far below ground level does the bottom of the poo

Yuri [45]

Answer:

a) 2.25 m

b) 2.625 m

Explanation:

Refraction is the name given to the phenomenon of the speed of light changing the the boundary when it moves from one physical medium to the other.

Refractive index is the ratio of the speed of light in empty vacuum (air is an appropriate substitution) to the speed of light in the medium under consideration.

In terms of real and apparent depth, the refractive index is given by

η = (real depth)/(apparent depth)

a) Real depth = 3.00 m

Apparent depth = ?

Refractive index, η = 1.333

1.333 = 3/(apparent depth)

Apparent depth = 3/1.3333 = 2.25 m.

Hence the bottom of the pool appears to be 2.25 m below the ground level.

b) Real depth = 1.5 m

Apparent depth = ?

Refractive index, η = 1.333

1.3333 = 1.5/(apparent depth)

Apparent depth = 1.5/1.3333 = 1.125 m

But the pool is half filled with water, there is a 1.5 m depth on top of the pool before refraction starts.

So, apparent depth of the pool = 1.5 + 1.125 = 2.625 m below the ground level

4 0

3 years ago

A block of mass m=16.8 kg is sliding on a surface with initial velocity v=23.2 m/s. The block has a coefficient of kinetic frict

Firdavs [7]

Answer:

t = 23.92 s

Explanation:

Newton's second law:

∑F = m*a Formula (1)

∑F : algebraic sum of the forces in Newton (N)

m : mass s (kg)

a : acceleration (m/s²)

We define the x-axis in the direction parallel to the movement of the block and the y-axis in the direction perpendicular to it.

Forces acting on the block

W: Weight of the block : In vertical direction, downward

FN : Normal force : perpendicular to the floor, upward

fk : Kinetic friction force: parallel to the floor and opposite to the movement

F = 86.4 N , in the direction of the motion

Calculated of the W

W= m*g

W= 16.8 kg* 9.8 m/s² = 164.64 N

Calculated of the FN

We apply the formula (1)

∑Fy = m*ay ay = 0

FN - W = 0

FN = W

FN = 164.64 N

Calculated of the fk

fk = μk*FN

fk = 0.426* 164.64 N

fk = 70.13 N

We apply the formula (1) to calculated acceleration of the block:

∑Fx = m*ax , ax= a : acceleration of the block

F - fk = m*a

86.4 -70.13 = (16.8)*(-a)

16.26 = (16.8)*(-a)

a = -(16.26 )/ (16.8)

a = - 0.97 m/s²

Kinematics of the block

Because the block moves with uniformly accelerated movement we apply the following formula :

vf = v₀ + a*t Formula (2)

Where:

t: time interval (m)

v₀: initial speed (m/s)

vf: final speed (m/s)

Data:

v₀ = 23.2 m/s

vf = 0

a = -0.97 m/s²

Time it takes for the block to stop

We replace data in the formula (2) to calculate the time

vf= v₀+a*t

0 = 23.2+( -0.97)*t

(0.97)*t = 23.2

t = 23.2 / (0.97)

t = 23.92 s

7 0

3 years ago

Calculate the Energy (E) in joules for that wavelength and record it in the table below. Remember that E = HF, where h the Planc

Viefleur [7K]

In that formula for Energy, 'F' is the frequency of the photon.
But <u>Frequency = (speed)/(wavelength)</u>, so we can write the
Energy formula as
   E = h c / (wavelength) .

So the energy, in joules, of a photon with that wavelength, is . . .

   E = (6.6 x 10⁻³⁴) x (3 x10⁸) / (that wavelength)

      = <em>(1.989 x 10⁻²⁵) / (that wavelength, in meters) .</em>

5 0

3 years ago

a boy takes 15min to reach his school on bicycle.if the bicycle have speed of 2m/s the what is the distance between the house an

Rom4ik [11]

<h2>Answer:</h2>

The distance will be 1800 m

<h2>Explanation</h2>

As in question

Time = 15 min

Time = 15 x 60 sec = 900 sec

Speed = 2 m/s

We know that