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2 years ago

Suppose a car approaches a hill and has an initial speed of

Physics

1 answer:

kvv77 [185]2 years ago

5 0

Answer:

a) 1.73*10^5 J

b) 3645 N

Explanation:

106 km/h = 106 * 1000/3600 = 29.4 m/s

If KE = PE, then

mgh = 1/2mv²

gh = 1/2v²

h = v²/2g

h = 29.4² / 2 * 9.81

h = 864.36 / 19.62

h = 44.06 m

Loss of energy = mgΔh

E = 780 * 9.81 * (44.06 - 21.5)

E = 7651.8 * 22.56

E = 172624.6 J

Thus, the amount if energy lost is 1.73*10^5 J

Work done = Force * distance

Force = work done / distance

Force = 172624.6 / (21.5/sin27°)

Force = 172624.6 / 47.36

Force = 3645 N

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Suppose that the sound level of a conversation is initially at an angry 71 dB and then drops to a soothing 54 dB. Assuming that

Goryan [66]

Answer:

Explanation:

In the decibel scale , intensity of sound changes logarithmically as follows

$10log\frac{I}{I_0} =$ Value in decibel scale , the value of I₀ = 10⁻¹² W /m².

Putting the values

$10log\frac{I}{10^{-12}} = 71$

$log\frac{I}{10^{-12}} = 7.1$

$\frac{I}{10^{-12}} = 10^{7.1}$

$I= 10^{-4.9}$ W/m²

Similarly for 54 dB sound intensity can be given as follows

I = 10⁻¹² x $10^{5.4}$

$I= 10^{-6.6 }$ W / m²

For intensity of sound the relation is as follows

I = 2π²υ²A²ρc where υ is frequency , A is amplitude , ρ is density of air and c is velocity of sound .

Putting the given values for 71 dB

$I= 10^{-4.9}$ = 2π² x 504²xA²x 1.21 x 346

A² = 60.03 x 10⁻¹⁶

A = 7.74 x 10⁻⁸ m

For 54 dB sound

$10^{-6.6}$ = 2π² x 504²xA²x 1.21 x 346

A² = 1.1978 x 10⁻¹⁶

A = 1.1 x 10⁻⁸ m

6 0

3 years ago

Which of these is the easiest mineral identification property to use when you want to know whether you have pyrite or actual gol

Makovka662 [10]

Answer:

c. streak

Explanation:

Pyrite is a mineral that looks like gold but actually is iron disulfide.

Pyrite and gold have comparable luster.

Pyrite and gold have different tones of yellow. This can be determined by their streak. Streak is the powdered form of a mineral. A streak of mineral can be found just by rubbing the mineral on a rough surface and comparing the colors.

Pyrite is diamagnetic which is not a strong form of magnetism. Gold is also diamagnetic

5 0

2 years ago

An electron in an atom has an uncertainty of 0.2 nm. If it is doubled to 0.4 nm by what factor does the uncertainty in momentum

fenix001 [56]

Answer:

The uncertainty in momentum changes by a factor of 1/2.

Explanation:

By Heisenberg's uncertainty principle, ΔpΔx ≥ h/2π where Δp = uncertainty in momentum and Δx = uncertainty in position = 0.2 nm. The uncertainty in momentum is thus Δp ≥ h/2πΔx. If the uncertainty in position is doubled, that is Δx₁ = 2Δx = 0.4 nm, the uncertainty in momentum Δp₁ now becomes Δp₁ ≥ h/2πΔx₁ = h/2π(2Δx) = (h/2πΔx)/2 = Δp/2.

So, the uncertainty in momentum changes by a factor of 1/2.

4 0

3 years ago

A student performed the following steps to find the solution to the equation x^2-2x-15=0 Where did the student go wrong? STEP 1:

AveGali [126]

B. In step 3

They incorrectly solved for x. It should have been x=-3 and x=5

3 0

3 years ago

Which of the following is true about scientific models? (2 points) Select one: a. Models are used to simplify the study of thing

Vanyuwa [196]

Question: Which of the following is true about scientific models? Select one: A) Models are used to simplify the study of things. B) Computer models are the most reliable kind of model. C) Models explain past, present and future information. D) A model is accurate if it does not change over time.

Answer: A) Models are used to simplify the study of things.

Hope this helps!.

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~A.W~ZoomZoom44

5 0

3 years ago

Read 2 more answers