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SIZIF [17.4K]
2 years ago
12

Our Sun emits most of its radiation at a wavelength of 550 nm. If a star were 3.50 times hotter than our Sun, it would emit most

of its radiation at a wavelength of _______ nm
Physics
1 answer:
Wittaler [7]2 years ago
8 0

The wavelength of the radiation emitted by the star is 183 nm.

Explanation:

As per Wien's displacement law, the product of emitted wavelength and temperature of the star will be equal to 2.898 × 10⁻³ mK.

T*wavelength = 2.898 * 10^{-3}

So if the wavelength of the emitted radiation by Sun is given as 550 nm, then the temperature of the Sun will be

Temperature of Sun = \frac{2.898*10^{-3} }{wavelength}

Temperature of Sun = \frac{2.898*10^{-3} }{550 * 10^{-9} } = 5.27 * 10^{3} K

Then if the temperature of star is said to be 3.5 times hotter than Sun, then the temperature of Star = 3.5×5.27×10³ = 15.81×10³ K.

With this temperature, the wavelength of the emitted radiation can be found as follows:

Wavelength = \frac{2.898 * 10^{-3} }{15.81 * 10^{3} } =183 nm

So, the wavelength of the radiation emitted by the star is 183 nm.

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A baseball catcher puts on an exhibition by catching a 0.15-kg ball dropped from a helicopter at a height of 101 m. What is the
yaroslaw [1]

Answer:

The speed of the ball 1.0 m above the ground is 44 m/s (Answer A).

Explanation:

Hi there!

To solve this problem, let´s use the law of conservation of energy. Since there is no air resistance, the only energies that we should consider is the gravitational potential energy and the kinetic energy. Because of the conservation of energy, the loss of potential energy of the ball must be compensated by a gain in kinetic energy.

In this case, the potential energy is being converted into kinetic energy as the ball falls (this is only true when there are no dissipative forces, like air resistance, acting on the ball). Then, the loss of potential energy (PE) is equal to the increase in kinetic energy (KE):

We can express this mathematically as follows:

-ΔPE = ΔKE

-(final PE - initial PE) = final KE - initial KE

The equation of potential energy is the following:

PE = m · g · h

Where:

PE = potential energy.

m = mass of the ball.

g = acceleration due to gravity.

h = height.

The equation of kinetic energy is the following:

KE = 1/2 · m · v²

Where:

KE = kinetic energy.

m = mass of the ball.

v = velocity.

Then:

-(final PE - initial PE) = final KE - initial KE          

-(m · g · hf - m · g · hi) = 1/2 · m · v² - 0     (initial KE = 0 because the ball starts from rest)  (hf = final height, hi = initial height)

- m · g (hf - hi) = 1/2 · m · v²

2g (hi - hf) = v²

√(2g (hi - hf)) = v

Replacing with the given data:

√(2 · 9.8 m/s²(101 m - 1.0 m)) = v

v = 44 m/s

The speed of the ball 1.0 m above the ground is 44 m/s.

3 0
2 years ago
Variations in the resistivity of blood can give valuable clues about changes in various properties of the blood. Suppose a medic
Elena-2011 [213]

Answer:

Answer:

1.1 x 10^9 ohm metre

Explanation:

diameter = 1.5 mm

length, l = 5 cm

Potential difference, V = 9 V

current, i = 230 micro Ampere = 230 x 10^-6 A

radius, r = diameter / 2 = 1.5 / 2 = 0.75 x 10^-3 m

Let the resistivity is ρ.

Area of crossection

A = πr² = 3.14 x 0.75 x 0.75 x 10^-6 = 1.766 x 10^-6 m^2

Use Ohm's law to find the value of resistance

V =  i x R

9 = 230 x 10^-6 x R

R = 39130.4 ohm

Use the formula for the resistance

R=\rho \frac{l}{A}

\rho =\frac{RA}{l}

\rho =\frac{39130.4\times 0.05}{1.766\times 10^{-6}}

ρ = 1.1 x 10^9 ohm metre

Explanation:

7 0
2 years ago
A car travels forward with constant velocity. It goes over a small stone, which gets stuck in the groove of a tire. The initial
puteri [66]

Answer:

A) vertically upward

Explanation:

Since the tyre is rotating with uniform angular speed and moving with constant linear speed

So as soon as a small stone is stuck into the groove of the tyre the speed of the stone is same as that of the tyre

so now we can say that stone will start revolving with the tyre of the car at constant angular speed and moving with uniform speed also

so here just after that the tangential acceleration of the stone must be zero while radial acceleration must be towards the center of the tyre given as

a_c = \omega^2 R

so we will have direction of net acceleration is towards its center so correct answer will be

A) vertically upward

7 0
2 years ago
The famous cliff divers of Acapulco leap from a perch 35 m above the ocean. How fast are they moving when they reach the surface
Rus_ich [418]

1) 26.2 m/s

The mechanical energy of the divers at any point of their vertical motion is sum of the kinetic energy and the gravitational potential energy:

E=K+U = \frac{1}{2}mv^2 + mgh

where

m is the mass of the diver

v is the speed

g = 9.8 m/s^2 is the acceleration due to gravity

h is the height above the water

When the diver is on the cliff, v = 0 (he is at rest), so K=0 and the initial mechanical energy is just potential energy:

E_i = mgh

where h=35 m is the height of the cliff.

When the diver hits the water above, h = 0, so U=0 and the final mechanical energy is just kinetic energy:

E_f = \frac{1}{2}mv^2

since the total mechanical energy is conserved, we have

E_i = E_f\\mgh = \frac{1}{2}mv^2

And solving the equation for v, we find the speed when they reach the surface of the water:

v=\sqrt{2gh}=\sqrt{2(9.8 m/s^2)(35 m)}=26.2 m/s

2) It is converted into thermal energy of the water

When the diver enters the water, he suddenly feels another force acting against the motion of the diver: the resistance of the water. The resistance of the water acts upward, slowing down the diver until he stops.

In this process, the speed of the diver (v) decreases, and therefore the kinetic energy of the diver decreases as well, until it becomes zero.

However, this does not mean that the conservation of energy has been violated. In fact, the kinetic energy of the diver has been converted into thermal energy of the molecules of water surrounding the diver.

8 0
2 years ago
A sharp edged orifice with a 50 mm diameter opening in the vertical side of a large tank discharges under a head of 5m. If the c
Sever21 [200]

Answer:

0.24

Explanation:

See attached file

3 0
2 years ago
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