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2 years ago

Help with the two questions above? Correct answers?

Physics

1 answer:

LenKa [72]2 years ago

7 0

(6) first choice: the frequency appears higher and wavelength is shorter.

The car approaches a stationary observer and so the sound will appear to have shorter wavelength. This creates an effect of its siren to sound with higher frequency than it would do if both were stationary.

(7) The Doppler formula for frequency in the case of a stationary observer and source approaching it is as follows:

$f_O = \frac{v}{v-v_s}\cdot f= \frac{343\frac{m}{s}}{(343-25)\frac{m}{s}}\cdot 400Hz \approx 431Hz$

The wavelength is then

$\lambda = \frac{343\frac{m}{s}}{431Hz}\approx 0.80 m$

The third choice "0.80m; 431Hz" is correct

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List 3 cases in which potential energy becomes kinetic energy and three cases in which kinetic energy becomes potential energy.

Mrrafil [7]

Answer:

when you open a can of pop

when you jump on your bed

Explanation:

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2 years ago

1. Which Law? When you are standing up in a subway train, and the train suddenly stops, your body continues to go forward.

riadik2000 [5.3K]

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3. Law 2, since you are giving the motorcycle more energy as a result of the gas being transformed into the energy that helps to accelerate the motorcycle's speed.

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2 years ago

#1 a person weighs 540n on earth what is the persons mass.

bixtya [17]

Answer:

G on earth =10N/Kg

W= mg

540= m x 10

m = 540/10

m= 54 Kg

W= mg

W= 66 x 10

W= 660 N

G on moon =1.6 N/Kg

W= mg

W= 54 x 1.6

W=86.4 N

W=mg

W= 66 x 1.6

W= 105.6 N

8 0

1 year ago

What is the instantaneous velocity of the hummingbird at t=1s?

Liono4ka [1.6K]

The distance - time graph of the humming bird is missing, so i have attached it.

Answer:

Instantaneous velocity = 0.5 m/s

Explanation:

From the attached graph, at time t = 1 s, the corresponding distance is 0.5 m.

Instantaneous velocity is the velocity at that point.

Thus;

Instantaneous velocity = 0.5/1

Instantaneous velocity = 0.5 m/s

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2 years ago

A 1.0-m-diameter vat of liquid is 2.0 m deep. The pressure at the bottom of the vat is 1.3 atm. What is the mass of the liquid i

gladu [14]

Answer:

The mass of the liquid = 10538 kg

Explanation:

The pressure in a liquid is

P = ρgh ......................... Equation 1

ρ = P/gh ...................... Equation 2

Where P = pressure, ρ = density, g = acceleration due to gravity, h = height.

Given: p = 1.3 atm, h = 2.0 m, g = 9.81 m/s²

If, 1 atm = 1.013×10⁵ N/m²

Then, P = 1.3×1.013×10⁵ N/m² = 1.3169×10⁵ N/m²

Substituting in equation 2,

ρ = 1.3169×10⁵/(9.81×2)

ρ = 1.3169×10⁵/19.62

ρ = 6712.03 kg/m³.

But Density,

ρ = m/v

m = ρ × v........................ Equation 3

Where m = mass of the liquid, v = volume of the liquid in the vat

v = πd²h/4, where d = diameter = 1.0 m, h = 2.0 m.

v = 3.14(1)²×2/4

v = 1.57 m³ also, ρ = 6712.03 kg/m³.

Substituting into equation 3

m = 1.57×6712.03

m = 10537.887 kg

m ≈ 10538 kg.

Thus the mass of the liquid = 10538 kg

3 0

3 years ago