That statement is flase. The index of refraction
of every material is more than 1.0 .
Given that,
At 3.00 m from a source that is emitting sound uniformly in all directions, the sound level is 60.0 dB.
To find,
The distance from the source would the sound level be one-fourth the sound level at 3.00 m.
Solution,
The intensity from a source is inversely proportional to the distance.
Let I₁ = 60 dB, r₁ = 3 m, I₂ = 60/4 = 15 dB, r₂ =?
Using relation :
So, at a distance of 6 m the sound level will be one fourth of the sound level at 3 m.
(a) work=Fd
<span>345x24=8280J </span>
<span>(b) work=Force of friction*d </span>
<span>Force of friction =coefficient*normal force=.22x1.5x10^3=330 </span>
<span>330*d=7920J </span>
<span>(c) net work =8280-7920=360J</span>
Pot conducts heat
Bin Insulates from heat
Plate Insulate from heat and brittle
Explanation:
Any material that is able to conduct heat is known as a conductor. Also, most heat conductors also allows electric current to pass through.
Most metals are categorized as heat conductors. A pot is usually made of conductors which helps to transfer heat to cook food.
Any material that does not conduct heat is called an insulator. Likewise, they do not allow electric current to pass through.
Most non-metals, plastics, rubber, wood, paper are insulators.
A brittle material that breaks into many pieces is a plastic. Their elastic limit is obviously exceeded and they lack internal cohesion and order. A glass used in making plate is also plastic and brittle.
learn more:
Conductors brainly.com/question/2474874
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<span>The 2nd truck was overloaded with a load of 16833 kg instead of the permissible load of 8000 kg.
The key here is the conservation of momentum.
For the first truck, the momentum is
0(5100 + 4300)
The second truck has a starting momentum of
60(5100 + x)
And finally, after the collision, the momentum of the whole system is
42(5100 + 4300 + 5100 + x)
So let's set the equations for before and after the collision equal to each other.
0(5100 + 4300) + 60(5100 + x) = 42(5100 + 4300 + 5100 + x)
And solve for x, first by adding the constant terms
0(5100 + 4300) + 60(5100 + x) = 42(14500 + x)
Getting rid of the zero term
60(5100 + x) = 42(14500 + x)
Distribute the 60 and the 42.
60*5100 + 60x = 42*14500 + 42x
306000 + 60x = 609000 + 42x
Subtract 42x from both sides
306000 + 18x = 609000
Subtract 306000 from both sides
18x = 303000
And divide both sides by 18
x = 16833.33
So we have the 2nd truck with a load of 16833.33 kg, which is well over it's maximum permissible load of 8000 kg. Let's verify the results by plugging that mass into the before and after collision momentums.
60(5100 + 16833.33) = 60(21933.33) = 1316000
42(5100 + 4300 + 5100 + 16833.33) = 42(31333.33) = 1316000
They match. The 2nd truck was definitely over loaded.</span>