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3 years ago

A book with a mass of 3.3 kg sits on a bookshelf. If it has a gravitational

Physics

1 answer:

erma4kov [3.2K]3 years ago

4 0

<h2><u>AnswEr :</u> </h2>

Given that,

Mass of the Book (M) = 3.3 Kg

Gravitational Potential Energy (P) = 57 J

Acceleration Due to Gravity (g) = 9.8 m/s²

We have to find the height of the shelf

We know that,

$\tt P = MgH$

Putting the values,

$\sf \: 57 = 3.3 \times 9.8 \times h \\ \\ \implies \: \sf \: 57 = 32.34 \times h \\ \\ \implies \: \sf \: h = 1.76 \: m \: (approx)$

<h3>The height of the shelf is 1.76 m </h3>

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Giving brainliest!! if you answer correctly :) (30pts)

myrzilka [38]

Answer:

mass = 4kg

Explanation:

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where m = mass and v = velocity

So,

KE = 50

1/2 × m × 5² = 50

1/2 × m × 25 = 50

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2 years ago

6.All wheelchairs may be secured so that the user is facing the curb side of the vehicle.

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All wheelchairs may be secured so that the user is facing the curb side of the vehicle is true. The answer is letter A. It provides a unique 180 degree powered rotation which makes it possible to raise, lower and rotate fully.

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3 years ago

A counterflow double-pipe heat exchanger is used to heat water from 20°C to 80°C at a rate of 1.2 kg/s. The heating is to be com

bixtya [17]

Answer:L=109.16 m

Explanation:

Given

initial temperature $=20^{\circ}C$

Final Temperature $=80^{\circ}C$

mass flow rate of cold fluid $\dot{m_c}=1.2 kg/s$

Initial Geothermal water temperature $T_h_i=160^{\circ}C$

Let final Temperature be T

mass flow rate of geothermal water $\dot{m_h}=2 kg/s$

diameter of inner wall $d_i=1.5 cm$

$U_{overall}=640 W/m^2K$

specific heat of water $c=4.18 kJ/kg-K$

balancing energy

Heat lost by hot fluid=heat gained by cold Fluid

$\dot{m_c}c(T_h_i-T_h_e)= \dot{m_h}c(80-20)$

$2\times (160-T)=1.2\times (80-20)$

$160-T=36$

$T=124^{\circ}C$

As heat exchanger is counter flow therefore

$\Delta T_1=160-80=80^{\circ}C$

$\Delta T_2=124-20=104^{\circ}C$

$LMTD=\frac{\Delta T_1-\Delta T_2}{\ln (\frac{\Delta T_1}{\Delta T_2})}$

$LMTD=\frac{80-104}{\ln \frac{80}{104}}$

$LMTD=91.49^{\circ}C$

heat lost or gain by Fluid is equal to heat transfer in the heat exchanger

$\dot{m_c}c(80-20)=U\cdot A\cdot$ (LMTD)

$A=\frac{1.2\times 4.184\times 1000\times 60}{640\times 91.49}=5.144 m^2$

$A=\pi DL=5.144$

$L=\frac{5.144}{\pi \times 0.015}$

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2 years ago

A 500 W hair dyer is used to dry hair for 6 minutes a day for 3 days. How much energy is used? A laptop uses 75 W. The cot of el

zzz [600]

Answer:

See the answers below.

Explanation:

We will solve this problem by calculating each part separately.

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The cots of electricity is 5.6 cents per kWh. How much would it cost to operate the laptop for 24 hours a day for one week?

We know that the power of the latop is 75 [W], then we can calculate the cost, multiplying the value of the power by the value of the cost by the time of use of the computer.

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A toaster oven is 85% efficient. It uses 1200 J of energy. How much thermal energy is it producing?

Efficiency is defined as the relationship between the energy obtained on the energy delivered. Almost always the energy delivered is greater than the energy obtained (first law of thermodynamics).

Therefore.

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2 years ago

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3 years ago