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4 years ago

Which of these statements is true?

2 answers:

7 0

B). Some elements found in nature exist as molecules.
That is, their atoms travel around in bound pairs.
Examples are Hydrogen, Oxygen, and Nitrogen.

A). No. Without atoms, you can't make a molecule.

C). No. A compound is a chemical combination of two or more elements.

D). No. An atom is the smallest unit of ONE single element.

Oduvanchick [21]4 years ago

5 0

Hello, your answer is, C. Some compounds include only one type of element.

I hope it helped!

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At the race track, one race car starts its engine with a resulting intensity level of 104.0 dB at point P. Then 6 more cars star

dem82 [27]

To solve the problem it is necessary to apply the concepts related to sound intensity. The most common approach to sound intensity measurement is to use the decibel scale:

$\beta (dB) = 10log_{10}(\frac{I}{I_0})$

Where,

$I_0 = 1*10^{-12}$ is a reference intensity. It is the lowest or threshold intensity of sound a person with normal hearing can perceive at a frequency of 1000 Hz.

I = Sound intensity

Our values are given by,

$\beta = 104dB$

$\#Autos = 7$

For each auto the intensity would be,

$104 = 10log\frac{I}{1*10^{-12}}$

$10.4= log_{10} (\frac{I}{10^{-12}})$

$10^{10.4}*10^{-12}=I$

$I = 0.02511W/m^2$

Therefore the sound intesity for the 7 autos is

$I= 7* 0.02511$

$I = 0.1748W/m^2$

The sound level for the 7 cars in dB is

$\beta (dB) = 10log_{10}(\frac{0.1748}{1*10^{-12}})$

$\beta (dB) = 112.42dB$

8 0

3 years ago

A 10 kg ball is held above a building with a height of 30 m. What is the

Darina [25.2K]

Answer: 2940 J

Explanation: solution attached:

PE= mgh

Substitute the values:

PE= 10kg x 9.8 m/s² x 30 m

= 2940 J

6 0

4 years ago

Olivia wants to find out whether a substance will fluoresce. She says she should put it in a microwave oven. Do you agree with h

andreyandreev [35.5K]

Disagree.
Fluoresce objects will only glow when put under actual Ultraviolet light. This is due to the molecules becoming excited by the ultraviolet radiation.

Microwaves give micro-waves that are present in another spectrum of wave length and will not be able to fluoresce the molecules. If it’s not “ultra violet “.... it’s not going to glow.

4 0

3 years ago

Read 2 more answers

A brave child decides to grab onto an already spinning merry‑go‑round. The child is initially at rest and has a mass of 34.5 kg.

rodikova [14]

Answer:

the moment of inertia of the merry go round is 38.04 kg.m²

Explanation:

We are given;

Initial angular velocity; ω_1 = 37 rpm

Final angular velocity; ω_2 = 19 rpm

mass of child; m = 15.5 kg

distance from the centre; r = 1.55 m

Now, let the moment of inertia of the merry go round be I.

Using the principle of conservation of angular momentum, we have;

I_1 = I_2

Thus,

Iω_1 = I'ω_2

where I' is the moment of inertia of the merry go round and child which is given as I' = mr²

Thus,

I x 37 = ( I + mr²)19

37I = ( I + (15.5 x 1.55²))19

37I = 19I + 684.7125

37I - 19 I = 684.7125

18I = 684.7125

I = 684.7125/18

I = 38.04 kg.m²

Thus, the moment of inertia of the merry go round is 38.04 kg.m²

7 0

4 years ago

Read 2 more answers

What are the name of variables that do not change through out and experiment?

kifflom [539]

Answer:

The answer is C

Explanation:

3 0

3 years ago

Read 2 more answers