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3 years ago

What do you understand by ?efficiency of a machine is 70%

Physics

1 answer:

tatuchka [14]3 years ago

8 0

Explanation:

The efficiency of a machine is 70% means 30% of the applied force is wasted in overcoming friction and 70% of the applied force is used to do the work

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What is the build up of electrons on a surface

Minchanka [31]

Answer:

Static energy

Explanation:

Think of it as a balloon rubbing against your hair, the two attractions of friction causes Static energy.

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3 years ago

Which of the following is represented by the letter A in the diagram below?

Kruka [31]

We have that the letter A in the diagram below given as

Amplitude

Option A

<h3>Amplitude</h3>

Question Parameters:

Amplitude

Crest

Trough

Wavelength

Generally, the amplitude of a wave is the maximum displacement of the wave in the medium from its initial position.

Amplitude is denoted with the letter A

Therefore,Amplitude

Option A

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2 years ago

What is the value of acceleration due to gravity at heght h=4re

Norma-Jean [14]

Answer: Formula for Acceleration Due to Gravity

These two laws lead to the most useful form of the formula for calculating acceleration due to gravity: g = G*M/R^2, where g is the acceleration due to gravity, G is the universal gravitational constant, M is mass, and R is distance.please mark as brainliest

Explanation:

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3 years ago

A 39-foot ladder is leaning against a vertical wall. If the bottom of the ladder is being pulled away from the wall at the rate

Viefleur [7K]

Answer:

The rate of change of the area when the bottom of the ladder (denoted by $b$ ) is at 36 ft. from the wall is the following:

$\frac{dA}{dt}|_{b=36}=-571.2\, ft^2/s$

Explanation:

The Area of the triangle is given by $A=h\times b$ where $h=\sqrt{l^2-b^2}$ (by using the Pythagoras' Theorem) and $b$ is the length of the base of the triangle or the distance between the bottom of the ladder and the wall.

The area is then

$A=\sqrt{l^2-b^2}b$

The rate of change of the area is given by its time derivative

$\frac{dA}{dt}=\frac{d}{dt}\left(\sqrt{l^2-b^2}\cdot b\right)$

$\implies \frac{dA}{dt}=\frac{d}{dt}\left(\sqrt{l^2-b^2}\right)\cdot b+\frac{db}{dt}\cdot\sqrt{l^2-b^2}$

$\implies\frac{dA}{dt}=\frac{1}{2\sqrt{l^2-b^2}}\frac{d}{dt}(l^2-b^2)\cdot b+\sqrt{l^2-b^2}}\cdot \frac{db}{dt}$ Product rule

$\implies\frac{dA}{dt}=-\frac{1}{2\sqrt{l^2-b^2}}\cdot 2\cdot b^2\cdot \frac{db}{dt}+\sqrt{l^2-b^2}}\cdot \frac{db}{dt}$ Chain rule

$\implies\frac{dA}{dt}=-\frac{1}{\sqrt{l^2-b^2}}\cdot b^2\cdot \frac{db}{dt}+\sqrt{l^2-b^2}}\cdot \frac{db}{dt}$

$\implies\frac{dA}{dt}=\frac{db}{dt}\left(-\frac{1}{\sqrt{l^2-b^2}}\cdot b^2+\sqrt{l^2-b^2}}\right)$

In here we can identify $b=36\, ft$ , $l=39$ and $\frac{db}{dt}=8\,ft/s$ .

The result is then

$\frac{dA}{dt}=8\left(-\frac{1}{\sqrt{39^2-36^2}}\cdot 36^2+\sqrt{39^2-36^2}}\right)=-571.2\, ft^2/s$

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3 years ago

Why are the trends for electronegativity and ionization energy similar

Goshia [24]

Answer:

Explanation:

Ionization Energy Trends

Ionization energy is the energy required to remove an electron from a neutral atom in its gaseous phase. Conceptually, ionization energy is the opposite of electronegativity. ... As a result, it is easier for valence shell electrons to ionize, and thus the ionization energy decreases down a group

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3 years ago

What do you understand by ?efficiency of a machine is 70%​

What do you understand by ?efficiency of a machine is 70%