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murzikaleks [220]
2 years ago
13

A person pushes a large 42.9 kg box at a constant velocity of 9 m/s across a horizontal floor for 3.8 s. Find the

Physics
1 answer:
Gwar [14]2 years ago
6 0

Answer:

10 kJ

Explanation:

W = Fd

W = (μN)(vt)

W = μ(mg)vt

W = 0.7(42.9)(9.81)(9)(3.8)

W = 10,075.12506 J

W ≈ 10 kJ

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kolbaska11 [484]
<h3>Question 1</h3>

Answer

option C) velocity

Explanation

acceleration =  Δv ÷ Δt

<h3>Question 2</h3>

Answer

option C) m/s²

Explanation

Δv ÷ Δt

= m/s ÷ s

= m/s x 1/s

= m/s²

<h3>Question 3</h3>

Answer

option B) velocity has both direction and speed.

That is why velocity can be negative but speed can not and velocity is rate of change of displacement where as speed is rate of change of distance.

7 0
3 years ago
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Properties seen when one substance changes to another are know as ____ properties
maxonik [38]

Answer: chemical property

Explanation:

6 0
2 years ago
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Which can a drop of liquid mercury can be described as?
Sophie [7]
Option D) A drop of mercury is both  a pure substance and and element.
Happy to assist you !
3 0
2 years ago
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When reaching a boundary between two media (1 and 2), an incident ray is partially reflected and partially refracted. The ray is
podryga [215]

Answer: critical angle, sin^-1 (n2/n1)

Explanation: the angle of incidence at which the retracted ray makes an angle of 90° with the normal is known as the critical angle.

Snell's law defined refraction mathematically as shown below

n1 sin θi = n2 sin θr

n1 = refractive index of the first medium

n2 = refractive index of the second medium

θi = angle of incidence

θr = angle of refraction

When the refrafted ray is perpendicular to the normal, the angle of refraction (θr) is 90° hence making the angle of incidence (θi) the critical angle θc

By substituting these conditions into the Snell's law, we have that

n1 sin θc = n2 sin 90

According to trigonometry, the value of sin 90 is 1, hence we have that

n1 sin θc =n2

sin θc = n2/n1

θc = sin^-1 (n2/n1)

3 0
2 years ago
Enrico Fermi (1901–1954) was a famous physicist who liked to pose what are now known as Fermi problems, in which several assumpt
Katarina [22]

Answer:

Explanation:

(a)

Since the earth is assumed to be a sphere.

Volume of atmosphere = volume of (earth +atm osphere) — volume of earth

= \frac{4}{3}\pi(6400+ 50)^3 -  \frac{4}{3}\pi (6400)&#10;^3\\\\=  \frac{4}{3}\pi(6192125000) km’^3\\= 2.6\times 10^{19} m^3

Hence the volume of atmosphere is 2.6\times 10^{19} m^3

(b)

Write the ideal gas equation as foll ows:

PV = nRT\\\\n\frac{0.20atm\times 2.6\times10^{19} m^3}{0.08206L\, atm/mok\, K \times (15+273+15)K}\times \frac{1L}{10^{-3}m^3}\\\\= 2.20\times 10^{20} moles

no.\, of\, molecules = 2.20\times 10^{20} moles \times \frac{6.022\times10^{23}\,molecules}{1mole}= 13.3\times10^{43} molecules&#10;

Hence the required molecules is 13.3\times10^{43} molecules&#10;

(c)

Write the ideal gas equation as follows:

PV =nRT&#10;\\\\n=\frac{1.0 atm \times 0.5L&#10;}{0.08206 L\, atm/mol\,K \times (37 +273.1 5)K} = 0.0196 moles

no.\, of\, molecules = 0.0196 moles \times\frac{6.022\times10^{23} molecules}&#10;{Imole}= 1.2\times 10^{23} molecules

Hence the required molecules in Caesar breath is 1.2\times 10^{23} molecules

(d)

Volume fraction in Caesar last breath is as follows:  

Fraction,\, X =\frac{12\times 10 molecules}{13.3\times 10^{43} \,molecules}= 9.0\times 10\, molecule/air\, molecule}

(e)

Since the volume capacity of the human body is 500 mL.

Volume\, of\, Caesar\, nreath\, inhale\, is =\frac{ 12\times 10^{22}\, molecules}{breath}\times \frac{9.0\times10^{-23} molecule}{air\, molecule}\\\\= 1.08 molecule/breath

5 0
2 years ago
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