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3 years ago

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Who showed that our universe is heliocentric—the planets of the solar system revolve around the sun? Johannes Kepler Isaac Newto

n Nicolaus Copernicus Galileo Galilei

1 answer:

denis23 [38]3 years ago

6 0

Answer:

Option (3)

Explanation:

Nicolaus Copernicus was an astronomer from Poland, who was born on the 19th of February in the year 1473. He played a great role in the field of modern astronomy.

He was the person who contributed to the heliocentric theory. This theory describes the position of the sun in the middle of the universe, and all the planets move around the sun. This theory was initially not accepted, and after about a century it was widely accepted.

This theory describes the present-day motion of the planets around the sun in the solar system. This theory replaced the geocentric theory.

Thus, the correct answer is option (3).

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Which of the following correctly describes the formula for speed?

Aleksandr [31]

Option C is the right answer

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3 years ago

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If a star is moving away from you at a constant speed, how do the wavelengths of the absorption lines change as the star gets fa

Minchanka [31]

Answer:

they stay shifted the same amount to the red

Explanation:

Redshift is given by

$z=\dfrac{\lambda_o-\lambda_e}{\lambda_e}$

Where,

$\lambda_o$ = Wavelength observed

$\lambda_e$ = Wavelength emitted

Also

Transverse redshift is given by

$1+z=\dfrac{1}{\sqrt{1-v^2/c^2}}$

v = Velocity of object

c = Speed of light = $3\times 10^8\ m/s$

So, if the velocity is constant the redshift remains the same

8 0

3 years ago

An electron travels west to east with a kinetic energy of 10 keV. The Earth's magnetic field in Pittsburgh is 19,911.5 nT in the

ch4aika [34]

Explanation:

It is given that,

Kinetic energy of the electron, $E_k=10\ keV=10^4\ eV=1.6\times 10^{-15}\ J$

Let the east direction is +x direction, north direction is +y direction and vertical direction is +z direction.

The magnetic field in north direction, $B_y=19911.5\ nT$

The magnetic field in west direction, $B_x=-3257.1\ nT$

The magnetic field in vertical direction, $B_z=48381.8 \ nT$

Magnetic field, $B=(-3257.1i+19911.5j+48381.8k)\ nT$

Firstly calculating the velocity of the electron using the kinetic energy formulas as :

$E_k=\dfrac{1}{2}mv^2$

$v=\sqrt{\dfrac{2E_k}{m}}$

$v=\sqrt{\dfrac{2\times 1.6\times 10^{-15}}{9.1\times 10^{-31}}}$

$v=5.92\times 10^7 i\ m/s$ (as it is moving from west to east)

The force acting on the charged particle in the magnetic field is given by :

$F=q(v\times B)$

$F=1.6\times 10^{-19}\times (5.92\times 10^7 i\times (-3257.1i+19911.5j+48381.8k)\times 10^{-9})$

Since, $i\times j=k\ \\j\times k=i\\k\times i=j$

And, $i\times i=j\times j=k\times k=0$

$F=1.6\times 10^{-19}\times [1178 k-2864.20j]$

$|F|=1.6\times 10^{-19}\times \sqrt{1178^2+2864.20^2}$

$F=4.95\times 10^{-16}\ N$

(b) Let a is the acceleration of the electron. It can be calculated as :

$a=\dfrac{F}{m}$

$a=\dfrac{4.95\times 10^{-16}}{9.1\times 10^{-31}}$

$a=5.43\times 10^{14}\ m/s^2$

Hence, this is the required solution.

4 0

3 years ago

Consider the potential energy diagram shown below. This graph shows the chemical potential energy in a reaction system over time

kolbaska11 [484]

Answer:

A. Endothermic reaction.

B. +150KJ.

C. 250KJ.

Explanation:

A. The graph represents endothermic reaction because the heat of the product is higher than the heat of the reactant.

B. Determination of the enthalpy change, ΔH for the reaction. This can be obtained as follow:

Heat of reactant (Hr) = 50KJ

Heat of product (Hp) = 200KJ

Enthalphy change (ΔH) =..?

Enthalphy change = Heat of product – Heat of reactant.

ΔH = Hp – Hr

ΔH = 200 – 50

ΔH = +150KJ

Therefore, the enthalphy change for the reaction is +150KJ

C. The activation energy for the reaction is the energy at the peak of the diagram.

From the diagram, the activation energy is 250KJ.

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3 years ago

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Sergeu [11.5K]

Force is transferred from the moving ball to the stationary ball.

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3 years ago

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