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2 years ago

What do astronomers mean by light pollution?

1 answer:

7 0

Light pollution is influence of the light on earth (for example, street lighting) which interrupt observations. For example, if you are in a street during the night and street lights are turned on you won't see stars, but if lighting is turned off or if you go out of town you will see stars above.

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During anomalous expansion of water ,heat transfer is limited to conduction and radiation only ,explain.

aalyn [17]

Heat transfer is limited to conduction and radiation only in anomalous expansion of water simply because of the temperature at which the expansion occurs and density

<h3>What is anomalous expansion of water?</h3>

Anomalous expansion of water is a property of water in which water expands instead of contracting.

Anomalous expansion of water makes water less dense.
The major effect of this anomalous expansion it will still remain less dense and at the surface of water.
Interestingly, this expansion occurs when it is cooled from 4°C to 0°C.

Learn more about properties of water:

brainly.com/question/18681949

4 0

1 year ago

How much mass should be attached to a vertical ideal spring having a spring constant (force constant) of 39.5 n/m so that it wil

mrs_skeptik [129]

The frequency of a simple harmonic oscillator such as a spring-mass system is given by
$f= \frac{1}{2 \pi} \sqrt{ \frac{k}{m} }$
where
k is the spring constant
m is the mass attached to the spring.

Re-arranging the formula, we get:
$m= \frac{k}{4 \pi^2 f^2}$
and since we know the constant of the spring:
$k=39.5 N/m$
and the frequency of oscillation:
f=1.00 Hz
we can find the value of the mass attached to it:
$m= \frac{39.5 Hz}{4 \pi^2 (1.00 Hz)^2} = 1.00 kg$

7 0

2 years ago

A wire 6.60 m long with diameter of 2.05 mm has a resistance of 0.0310 Ω.

Alex73 [517]

Answer:

1.551×10^-8 Ωm

Explanation:

Resistivity of a material is expressed as shown;.

Resistivity = RA/l

R is the resistance of the material

A is the cross sectional area

l is the length of the wire.

Given;

R = 0.0310 Ω

A = πd²/4

A = π(2.05×10^-3)²/4

A = 0.000013204255/4

A = 0.00000330106375

A = 3.30×10^-6m

l = 6.60m

Substituting this values into the formula for calculating resistivity.

rho = 0.0310× 3.30×10^-6/6.60

rho = 1.023×10^-7/6.60

rho = 1.551×10^-8 Ωm

Hence the resistivity of the material is 1.551×10^-8 Ωm

6 0

2 years ago

If the moon is rising at midnight, the phase of the moon must be

Nadya [2.5K]

The phase is called 3rd quarter.

Hope this helps:)

7 0

3 years ago

A force of 250 N is applied to a hydraulic jack piston that is 0.02 m in diameter. If the piston that supports the load has a di

Vikentia [17]

Answer:

option B

Explanation:

given,

Force exerted by the hydraulic jack piston = F₁ = 250 N

diameter of piston, d₁ = 0.02 m

r₁ = 0.01 m

diameter of second piston, d₂ = 0.15 m

r₂ = 0.075 m

mass of the jack to lift = ?

now,

$\dfrac{F_1}{A_1} =\dfrac{F_2}{A_2}$

$\dfrac{250}{\pi r_1^2} =\dfrac{F_2}{\pi r_2^2}$

$\dfrac{250}{0.01^2} =\dfrac{F_2}{0.075^2}$

$F_2= \dfrac{250}{0.01^2}\times {0.075^2}$

F₂ = 14062.5 N

F = m g

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

$m = \dfrac{14062.5}{9.8}$

m = 1435 Kg

hence, the correct answer is option B

5 0

3 years ago