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zavuch27 [327]
2 years ago
11

People often use simple machines like pulleys, levers, and ramps because they say the machine “makes the work easier.” Which of

the following statements about simple machines is true?
a.
Simple machines often reduce the amount of work to move an object.

b.
Simple machines often reduce the energy required to move an object.

c.
Simple machines often reduce the power consumed when moving an object.

d.
Simple machines often reduce the force needed to move an object.
Physics
1 answer:
dimulka [17.4K]2 years ago
3 0
I think the answer is D.
Hope this help
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Answer:

c

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Frequency is the ____________ that move past a point during a specific amount of time. Frequency is measured in ____________ , a
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Answer:

Frequency is <u>the number of waves</u> that move past a point during a specific amount of time. Frequency is measured in <u>Hertz</u>, and is classified as high, medium, or low. Frequency is interpreted as the <u>pitch</u> of a sound. Intensity refers to the <u>loudness</u> of a sound and is measured in <u>decibels</u>. Louder sounds <u>increase</u> the rate of nerve signals relayed to the brain.

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3 years ago
Water is boiled at sea level in a coffeemaker equipped with an immersion-type electric heating element. The coffee maker contain
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Answer:

P=1362\ W

t'=251.659\ s is time required to heat to boiling point form initial temperature.

Explanation:

Given:

initial temperature of water, T_i=18^{\circ}C

time taken to vapourize half a liter of water, t=18\ min=1080\ s

desity of water, \rho=1\ kg.L^{-1}

So, the givne mass of water, m=1\ kg

enthalpy of vaporization of water, h_{fg}=2256.4\times 10^{-3}\ J.kg^{-1}

specific heat of water, c=4180\ J.kg^{-1}.K^{-1}

Amount of heat required to raise the temperature of given water mass to 100°C:

Q_s=m.c.\Delta T

Q_s=1\times 4180\times (100-18)

Q_s=342760\ J

Now the amount of heat required to vaporize 0.5 kg of water:

Q_v=m'\times h_{fg}

where:

m'=0.5\ kg= mass of water vaporized due to boiling

Q_v=0.5\times 2256.4

Q_v=1.1282\times 10^{6}\ J

Now the power rating of the boiler:

P=\frac{Q_s+Q_v}{t}

P=\frac{342760+1128200}{1080}

P=1362\ W

Now the time required to heat to boiling point form initial temperature:

t'=\frac{Q_s}{P}

t'=\frac{342760}{1362}

t'=251.659\ s

6 0
3 years ago
"what information does the slope of the line give you when graphing the pressure versus 1/volume at constant temperature for 1 m
Rashid [163]
Hello!

The slope of the line given by graphing pressure vs 1/Volume at constant temp for one mole of gas will give you the value for nRT from equation PV=nRT

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6 0
3 years ago
A rough estimate of the radius of a nucleus is provided by the formula r 5 kA1/3, where k is approximately 1.3 × 10213 cm and A
Sphinxa [80]

Answer:

Density of 127 I = \rm 1.79\times 10^{14}\ g/cm^3.

Also, \rm Density\ of\ ^{127}I=3.63\times 10^{13}\times Density\ of\ the\ solid\ iodine.

Explanation:

Given, the radius of a nucleus is given as

\rm r=kA^{1/3}.

where,

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The density of the nucleus is defined as the mass of the nucleus M per unit volume V.

\rm \rho = \dfrac{M}{V}=\dfrac{M}{\dfrac 43 \pi r^3}=\dfrac{M}{\dfrac 43 \pi (kA^{1/3})^3}=\dfrac{M}{\dfrac 43 \pi k^3A}.

For the nucleus 127 I,

Mass, M = \rm 2.1\times 10^{-22}\ g.

Mass number, A = 127.

Therefore, the density of the 127 I nucleus is given by

\rm \rho = \dfrac{2.1\times 10^{-22}\ g}{\dfrac 43 \times \pi \times (1.3\times 10^{-13})^3\times 127}=1.79\times 10^{14}\ g/cm^3.

On comparing with the density of the solid iodine,

\rm \dfrac{Density\ of\ ^{127}I}{Density\ of\ the\ solid\ iodine}=\dfrac{1.79\times 10^{14}\ g/cm^3}{4.93\ g/cm^3}=3.63\times 10^{13}.\\\\\Rightarrow Density\ of\ ^{127}I=3.63\times 10^{13}\times Density\ of\ the\ solid\ iodine.

7 0
3 years ago
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