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2 years ago

Which of the following would be the best thermal conductor?

Physics

2 answers:

Elis [28]2 years ago

4 0

The best thermal conductor is b. metal

r-ruslan [8.4K]2 years ago

3 0

Answer: Option (b) is the correct answer.

Explanation:

A material through which energy can travel in the form of heat without any movement of material itself is known as a thermal conductor.

It is known that metals are good conductors of heat and electricity. Hence, they act as good thermal conductors.

Thus, we can conclude that out of the given options metal would be the best thermal conductor.

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A police car is driving down the street with it's siren on. You are standing still on the sidewalk beside the street. If the fre

AleksandrR [38]

Answer:

A) 1568.60 Hz

B) 1437.15 Hz

Explanation:

This change is frequency happens due to doppler effect

The Doppler effect is the change in frequency of a wave in relation to an observer who is moving relative to the wave source

$f_(observed)=\frac{(c+-V_r)}{(C+-V_s)} *f_(emmited)\\$

where

C = the propagation speed of waves in the medium;

Vr= is the speed of the receiver relative to the medium,(added to C, if the receiver is moving towards the source, subtracted if the receiver is moving away from the source;

Vs= the speed of the source relative to the medium, added to C, if the source is moving away from the receiver, subtracted if the source is moving towards the receiver.

A) Here the Source is moving towards the receiver(C-Vs)

and the receiver is standing still (Vr=0) therefore the observed frequency should get higher

$f_(observed)=\frac{C}{C-V_s} *f_(emmited)\\=\frac{343}{343-15}*1500\\ =1568.60 Hz$

B)Here the Source is moving away the receiver(C+Vs)

and the receiver is still not moving (Vr=0) therefore the observed frequency should be lesser

$f_(observed)=\frac{C}{C+V_s} *f_(emmited)\\=\frac{343}{343+15}*1500\\ =1437.15 Hz$

3 0

2 years ago

If you weigh 882 N on EARTH (HINT: What number do we ALWAYS use for gravity on Earth), what is your mass?

Softa [21]

882 divided by 9.81 (this is acceleration due to gravity) it equals 89.91

4 0

2 years ago

A potential difference of 1.20 V will be applied to a 33.0 m length of 18-gauge copper wire (diameter = 0.0400 in.). Calculate (

Nostrana [21]

Answer:A) Current = 1.739A, B)current density, J = 2.147x10^6 A/m2

magnitude of electric field , E = 0.036 N/C

)rate of thermal energy, P =2.086W

Explanation:

Resistance = R = ρL/A

But the cross-section area of the wire. is given as

Diameter / 2 = 0.04/2 =0.02in to m = 0.02 / 39.37= 0.000508

A = πr^2 = π x 0.000508^2 = 8.10 x 10^-7

since resistivity of copper,ρ= 17x10-9 ohm.m

so resistance is R = ρL/A

17x10-9 x 33 / 8.1x10-7

= 0.69 ohm.

A) Current = I = Voltage /Resistance =1.20/0.69 =1.739A

B)current density, J = Current /Area

= 1.739/8.1x10-7

= 2.147x10^6 A/m2

c)magnitude of electric field , E = Current density x resistivity =J ρ

E = 2.147 x 10^6 x 17 x 10^-9

E = 0.036 N/C

D)rate of thermal energy, P = I² R =1.739² X 0.69

=2.086W

6 0

2 years ago

How do your shoe laces relate to a pulley

Margarita [4]

The grommets on your shoe (Holes through which you place the lace) act as the pulley. When you tighten at the top it restricts at the bottom and compresses around your foot.

The same can be applied to a pulley; If you have the proper set up Pulling one string causes two actions; the first being the most obvious. And the second being its effect. The Grommets of your shoe are the pulley's; while your Shoelaces are just the rope with which you operate the pulley.

8 0

3 years ago

If x =(20-4t^2) find average velocity between t=0and t=2sec

lapo4ka [179]

Answer:

The average velocity is 8 unit per sec

Explanation:

Given as :

The Distance x = 20 - 4t² unit

Change in time Δt = ( 2 - 0 ) s = 2 s

Let the velocity = V unit/s

∴ V = $\frac{\partial (20 - 4t^{2})}{\partial x}$