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shtirl [24]
3 years ago
15

A star has a surface temperature of 30,000 K. At what wavelength does the peak radiation occur? 100 nm

Physics
2 answers:
tangare [24]3 years ago
8 0
Use the displacement law, peak wavelength = 0.0029/T =0.0029/30000 = 97nm
Eva8 [605]3 years ago
8 0

Answer : Wavelength is 97 nm.

Explanation :

It is given that,

The surface temperature of a star, T=30,000\ K

We have to find the wavelength where the peak radiation occurs.

We can find the wavelength using Wein's displacement law i.e.

\lambda=\dfrac{b}{T}

b is the Wein's constant b=2.88\times 10^{-3}m.K

So, \lambda=\dfrac{2.88\times 10^{-3}\ m.K}{30,000\ K}

\lambda=9.6\times 10^{-8}\ m

or \lambda=97\ nm

Hence, the correct option is (b).        

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Breanna is standing beside a merry-go-round pushing 19° from the tangential direction and is able to accelerate the ride and her
leva [86]

To solve the problem it is necessary to apply the concepts given in the kinematic equations of angular motion that include force, acceleration and work.

Torque in a body is defined as,

\tau_l = F*d

And in angular movement like

\tau_a = I*\alpha

Where,

F= Force

d= Distance

I = Inertia

\alpha = Acceleration Angular

PART A) For the given case we have the torque we have it in component mode, so the component in the X axis is the net for the calculation.

\tau= F*cos(19)*d

On the other hand we have the speed data expressed in RPM, as well

\omega_f = 10rpm = 10\frac{1rev}{1min}(\frac{1min}{60s})(\frac{2\pi rad}{1rev})

\omega_f = 1.0471rad/s

Acceleration can be calculated by

\alpha = \frac{\omega_f}{t}

\alpha = \frac{1.0471}{9}

\alpha = 0.11rad/s^2

In the case of Inertia we know that it is equivalent to

I = \frac{1}{2}mr^2 = \frac{1}{2}(750)*(2.3)^2

I = 1983.75kg.m^2

Matching the two types of torque we have to,

\tau_l=\tau_a

Fd=I\alpha

Fcos(19)*2.3=1983.75(0.11)

F=100.34N

PART B) The work performed would be calculated from the relationship between angular velocity and moment of inertia, that is,

W = \frac{1}{2}I\omega_f^2

W= \frac{1}{2}(1983.75)(1.0471)^2

W=1087.51J

7 0
2 years ago
a magnet has a 20 cm magnetic field if a piece of metal is 18 cm from the magnet will it be attracted or not
mina [271]

Answer:

yes

Explanation:

The metal is closer than 20 cm to the magnet which is in the magnetic field.

4 0
3 years ago
A uniform marble rolls down a symmetrical bowl, start- ing from rest at the top of the left side. The top of each side is a dist
Paha777 [63]

Answer:

Part a)

h' = \frac{10}{14} h

Part b)

if both sides are rough then it will reach the same height on the other side because the energy is being conserved.

Part c)

Since marble will go to same height when it is rough while when it is smooth then it will go to the height

h' = \frac{10}{14} h

so on smooth it will go to lower height

Explanation:

As we know by energy conservation the total energy at the bottom of the bowl is given as

\frac{1}{2} mv^2 + \frac{1}{2}I\omega^2 = mgh

here we know that on the left side the ball is rolling due to which it is having rotational and transnational both kinetic energy

now on the right side of the bowl there is no friction

so its rotational kinetic energy will not change and remains the same

so it will have

\frac{1}{2}mv^2 = mgh'

now we know that

I = \frac{2}{5}mr^2

\omega = \frac{v}{r}

so we have

\frac{1}{2}mv^2 + \frac{1}{2}(\frac{2}{5}mr^2)(\frac{v}{r})^2 = mgh

\frac{1}{2}mv^2 + \frac{1}{5}mv^2 = mgh

\frac{7}{10}mv^2 = mgh

\frac{1}{2}mv^2 = \frac{10}{14}mgh

so the height on the smooth side is given as

h' = \frac{10}{14} h

Part b)

if both sides are rough then it will reach the same height on the other side because the energy is being conserved.

Part c)

Since marble will go to same height when it is rough while when it is smooth then it will go to the height

h' = \frac{10}{14} h

so on smooth it will go to lower height

6 0
3 years ago
Read 2 more answers
In the picture of a planet in orbit around its star area a is double that of area b. What is true of the time the planet takes t
aalyn [17]
The Kepler's laws predict the planetary motion, so there are three laws for this, namely:

1. The orbit of a planet is an ellipse with the Sun (the sun is a star!) at one of the two focus.

2. A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time.

3. The square of the orbital period of a planet is proportional to the cube of the semi-major axis of its orbit.

So, let's use second law. The Sun sweeps out equal areas during equal intervals of time means that if A = B, the time the planet takes to travel A1A2 is equal to the time the planet takes to travel B1B2, but given that A = 2B, then takes twice the time to travel A1A2 compared to B1B2.
8 0
3 years ago
In the context of energy transfers with hot and cold reservoirs, the sign convention is that _______________.
Likurg_2 [28]

Answer:

B. QC > 0; QH < 0

Explanation:

Given that there are two reservoir of energy.

Sign convention for heat and work :

1.If the heat is adding to the system then it is taken as positive and if heat is going out from the system then it is taken as negative.

2. If the work is done on the system then it is taken as negative and if the work is done by the system then it is taken as positive.

From hot reservoir heat is going out that is why it is taken as negative

Q_H

From cold reservoir heat is coming inside the reservoir that is why it is taken as positive

Q_C>0

That is why the answer will be

Q_H ,Q_C>0

8 0
3 years ago
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