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chubhunter [2.5K]
3 years ago
10

A 51-kg woman runs up a vertical flight of stairs in 5.0 s. Her net upward displacement is 5.0 m. Approximately, what average po

wer did the woman exert while she was running?
Physics
1 answer:
Vika [28.1K]3 years ago
6 0

Answer:

The average power the woman exerts is 0.5 kW

Explanation:

We note that power, P = The rate at which work is done = Work/Time

Work = Energy

The total work done is the potential energy gained which is the energy due to vertical displacement

Given that the vertical displacement = 5.0 m, we have

Total work done = Potential energy gained = Mass, m × Acceleration due to gravity, g × Vertical height, h

m = 51 kg

g = Constant = 9.81 m/s²

h = 5.0 m

Also, time, t = 5.0 s

Total work done = 51 kg × 9.81 m/s²× 5 m = 2501.55 kg·m²/s² = 2501.55 J

P = 2501.55 J/(5 s) = 500.31 J/s = 500.31 W ≈ 500 W = 0.5 kW.

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Answer:

\triangle V = 0.02484m^3

Explanation:

Given

V_1 = 3.00m^3 --- initial volume

T_1 = 20.0^oC --- initial temperature

T_2 = 60.0^oC --- final temperature

\gamma = 207*10^{-6 ---  coefficient of thermal expansion:

Required

The change in volume

To do this, we make use of cubic expansivity formula

\triangle V = \gamma * V_2 * (T_2 - T_1)

So, we have:

\triangle V = 207 * 10^{-6} * 3.00 * (60.0 - 20.0)

\triangle V = 207 * 10^{-6} * 3.00 * 40.0

\triangle V = 0.02484m^3

The volume will expand by 0.02484m^3

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Heterogeneous Mixture And Homogeneous Mixture
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Answer: Go ask your teacher and im sure if you search it on good it will answer faster than this.

Explanation: Have a great day \ and be safe

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What percentage of diabetes patients have type 2?
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Read 2 more answers
A 2.4-m high 200-m2 house is maintained at 22°C by an air-conditioning system whose COP, is 3.2. It is estimated that the kitch
kotegsom [21]

Answer:

The amount that is "vented" out by "the fans" is <u>$0.50</u> for 10 hours.

Option: a

<u>Explanation</u>:

"Energy discharged by air in every hour" can be determined by,

\mathrm{Q}=\mathrm{m}_{\mathrm{air}} \mathrm{C}_{\mathrm{p}} \Delta \mathrm{T}

Q = heat energy (Joules, J)  

m = mass of a substance (kg)  

c = specific heat (units J/kg∙K)  

\mathrm{m}_{\mathrm{air}}=\rho \mathrm{v}

\text { Density of air } \rho=1.20 \mathrm{kg} / \mathrm{m}^{3}

\text { Density of air } \rho=1.20 \times 200 \times 2.4

\text { Density of air } \rho=576 \mathrm{kg}

∆T = 10 hours

\text { Specific Heat Capacities of Air. The nominal values used for air at } 300 \mathrm{K} \text { are } \mathrm{C_P}=1.00 \mathrm{kJ} / \mathrm{kg} . \mathrm{K}

Q = 576 × 1.00 × 10

Q = 5760 kJ/hours

W = 1.6 kwh

We know that, “Coefficient of performance” (COP)

\mathrm{Cop}=\frac{Q}{w}

\mathrm{W}=\frac{Q}{\mathrm{cop}}

Given that, COP = 3.2

\mathrm{W}=\frac{1.6}{3.2}

W = 0.5 kwh

The unit cost of electricity is $0.10/kWh

The unit cost of electricity is $0.10/kWh

Unit electricity cost for 10 hours = 0.5 × 10 × 0.1$

Unit electricity cost for 10 hours = $0.5

The amount that is "vented out" by "the fans" is $0.50 for 10 hours.

6 0
3 years ago
A police car is traveling due east at a speed of 15.0 m/s relative to the earth. You are in a convertible following behind the p
Neporo4naja [7]

Answer:

A.) 355 m/s

B.) 0.71 m

C.) 500Hz

Explanation:

Given that a police car is traveling due east at a speed of 15.0 m/s relative to the earth. You are in a convertible following behind the police car. Your car is also moving due east at 15.0 m/s relative to the earth, so the speed of the police car relative to you is zero. The siren of the police car is emitting sound of frequency 500 Hz. The speed of sound in the still air is 340 m/s

a.) What is the speed of the sound waves relative to you?

Since the car is moving away from the observer, the relative velocity will be:

Relative velocity = 340 + 15

Relative velocity = 355 m/s

b.) What is the wavelength of the sound waves at your location?

Using the wave speed formula

V = frequency × wavelength

Make wavelength the subject of formula.

Wavelength = Velocity / frequency

Wavelength = 355/500

Wavelength = 0.71 m

c.) What frequency do you detect?

Fo = Fs ( C + V ) / ( C + v )

Fo = Fs

That is, the frequency of the observer will be equal to the frequency of the source.

Therefore, Fo = 500Hz

4 0
3 years ago
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