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3 years ago

If Mike does 25.5 J of work lifting a book 1.5 m onto a shelf what is the mass of the book in kilograms

1 answer:

7 0

Lifting the book means that the object gains gravitational potential energy. GPE=mass*gravitational field strength*height, ∴m=GPE/gh, m=25.5/10*1.5=1.7 kg

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Water is being boiled in an open kettle that has a 0.52-cm-thick circular aluminum bottom with a radius of 12.0 cm. If the water

tangare [24]

Answer:

$T_b=107.3784\ ^{\circ}C$

Explanation:

Given:

thickness of the base of the kettle, $dx=0.52\ cm=5.2\times 10^{-3}\ m$

radius of the base of the kettle, $r=0.12\ m$

temperature of the top surface of the kettle base, $T_t=100^{\circ}C$

rate of heat transfer through the kettle to boil water, $\dot Q=0.409\ kg.min^{-1}$

We have the latent heat vaporization of water, $L=2260\times 10^3\ J.kg^{-1}$

and thermal conductivity of aluminium, $k=240\ W.m^{-1}.K^{-1}$

So, the heat rate:

$\dot Q=\frac{0.409\times 2260000}{60}$

$\dot Q=15405.67\ W$

From the Fourier's law of conduction we have:

$\dot Q=k.A.\frac{dT}{dx}$

$\dot Q=k\times \pi.r^2\times \frac{T_b-T_t}{5.2\times 10^{-3}}$

where:

$A=$ area of the surface through which conduction occurs

$T_b=$ temperature of the bottom surface

$15405.67=240\times \pi\times 0.12^2\times \frac{T_b-100}{5.2\times 10^{-3}}$

$T_b=107.3784\ ^{\circ}C$ is the temperature of the bottom of the base surface of the kettle.

6 0

4 years ago

What is the equivalent resistance of the circuit?

Sonbull [250]

Answer:

80Ω

Explanation:

Resistance in a series circuit (when one resistor is after another in the same line) is calculated with the following equation

Total resistance = R1 + R2 + R3...Rn

Substitute in your values and solve for total resistance

Total resistance = 60 + 20 = 80Ω

8 0

3 years ago

Read 2 more answers

10. Explain the principle of electric motor. Write its uses.

konstantin123 [22]

Explanation:

The principle of an electric motor is based on the current carrying conductor which produces magnetic field around it. A current carrying conductor is placed perpendicular to the magnetic field so that it experiences a force.

The largest electric motors are used for ship propulsion, pipeline compression and pumped-storage applications with ratings reaching 100 megawatts. Electric motors are found in industrial fans, blowers and pumps, machine tools, household appliances, power tools and disk drives.

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3 years ago

Which of the following pulley systems have/has a greater mechanical advantage than the one shown above?

astraxan [27]

Is there a picture or description?

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3 years ago

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The density, or intensity, of a magnetic field is called flux. True False

aev [14]

Answer:

True :)