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2 years ago

Why machines are never 100 percent efficient

2 answers:

8 0

Machines are never 100% efficient because they are made by humans and we make errors and nothing we make is perfect, that's why the machines we build are not 100% accurate or efficient.

algol132 years ago

4 0

<span>The efficiency of an actual machine is never 100% because of the Second law of thermodynamics which states that the quality of energy will decay, eventually becoming heat. This means that some of the work put into the system is transformed (lost) into thermal energy(heat) therefore, causing the percent to reduce.</span>

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What type of material does not transfer heat well?

scZoUnD [109]

Insulators such as wood

6 0

3 years ago

At what point is the northern hemisphere pointed farthest away from the sun?

inna [77]

<span>Well, It is the aphelion point, When the Earth is farthest away from the Sun, when the Northern Hemisphere is warm. the Earth is closest to the Sun, or at the perihelion, 2 weeks after the June Solstice, when the Northern Hemisphere is enjoying warm summer months. Well this kind of weather is very nice.</span>

7 0

2 years ago

Air pressure may be represented as a function of height above the surface of the Earth as shown below.. P(h) = P_0 e^-.00012h. .

Rufina [12.5K]

Answer. Second Option: .85p_o=p_o e^-.00012h

Solution:

P(h)=Po e^(-0.00012h)

Air pressure: P(h)

Height above the surface of the Earth (in meters): h

Air pressure at the sea level: Po

Height at which air pressure is 85% of the air pressure at sea level:

h=?, P(h)=85% Po

P(h)=(85/100) Po

P(h)=0.85 Po

Replacing P(h) by 0.85 Po in the formula above:

P(h)=Po e^(-0.00012h)

0.85 Po = Po e^(-0.00012h)

5 0

2 years ago

Read 2 more answers

Suppose the rocket in the Example was initially on a circular orbit around Earth with a period of 1.6 days. Hint (a) What is its

ruslelena [56]

Answer:

The orbital speed is $v= 2.6*10^{3} m/s$

The escape velocity of the rocket is $v_e= 3.72 *10^3 m/s$

Explanation:

Generally angular velocity is mathematically represented as

$w = \frac{2 \pi}{T}$

Where T is the period which is given as 1.6 days = $1.6 *24 *60*60 = 138240 sec$

Substituting the value

$w = \frac{2 \pi}{138240}$

$= 4.54*10^ {-5} rad /sec$

At the point when the rocket is on a circular orbit

The gravitational force = centripetal force and this can be mathematically represented as

$\frac{GMm}{r^2} = mr w^2$

Where G is the universal gravitational constant with a value $G = 6.67*10^{-11}$

M is the mass of the earth with a constant value of $M = 5.98*10^{24}kg$

r is the distance between earth and circular orbit where the rocke is found

Making r the subject

$r = \sqrt[3]{\frac{GM}{w^2} }$

$= \sqrt[3]{\frac{6.67*10^{-11} * 5.98*10^{24}}{(4.45*10^{-5})^2} }$

$= 5.78 *10^7 m$

The orbital speed is represented mathematically as

$v=wr$

Substituting value

$v= (5.78*10^7)(4.54*10^{-5})$

$v= 2.6*10^{3} m/s$

The escape velocity is mathematically represented as

$v_e = \sqrt{\frac{2GM}{r} }$

Substituting values

$= \sqrt{\frac{2(6.67*10^{-11})(5.98*10^{24})}{5.78*10^7} }$

$v_e= 3.72 *10^3 m/s$

7 0

3 years ago

A 50-cm-long spring is suspended from the ceiling. A 270 g mass is connected to the end and held at rest with the spring unstret

I am Lyosha [343]

Answer:

The spring constant is 45.94 N/m.

Explanation:

Given that,

Length = 50 cm

Mass = 270 g

Stretching the spring = 24 cm

We need to calculate the spring constant

Using formula of energy

The change in potential energy equal to the change in kinetic energy.

$mgh=\dfrac{1}{2}kx^2$

Put the value into the formula

$270\times10^{-3}\times9.8\times50\times10^{-2}=\dfrac{1}{2}\times k\times(24\times10^{-2})^2$

$k=\dfrac{2\times270\times10^{-3}\times9.8\times50\times10^{-2}}{(24\times10^{-2})^2}$

$k=45.94\ N/m$

Hence, The spring constant is 45.94 N/m.

3 0

2 years ago