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3 years ago

5

As an airplane files, the airplane pushes against air. This resistance is called drag. What force does drag work against? A) ene

rgy B) lift C) thrust D) weight

2 answers:

Anna [14]3 years ago

3 0

Drag is opposing Thrust. Hope this Helps.

ozzi3 years ago

3 0

The answer is

C) Thrust

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Bare free charges do not remain stationary when close together. To illustrate this, calculate the acceleration of two isolated p

Marta_Voda [28]

Answer:

Acceleration, $a=9.91\times 10^{15}\ m/s^2$

Explanation:

It is given that,

Separation between the protons, $r=3.73\ nm=3.73\times 10^{-9}\ m$

Charge on protons, $q=1.6\times 10^{-19}\ C$

Mass of protons, $m=1.67\times 10^{-27}\ kg$

We need to find the acceleration of two isolated protons. It can be calculated by equating electric force between protons and force due to motion as :

$ma=\dfrac{kq^2}{r^2}$

$a=\dfrac{kq^2}{mr^2}$

$a=\dfrac{9\times 10^9\times (1.6\times 10^{-19})^2}{1.67\times 10^{-27}\times (3.73\times 10^{-9})^2}$

$a=9.91\times 10^{15}\ m/s^2$

So, the acceleration of two isolated protons is $9.91\times 10^{15}\ m/s^2$ . Hence, this is the required solution.

3 0

3 years ago

Accuracy and precision

igomit [66]

Explanation:

measurement of a set, accuracy is closeness of the measurements to a specific value, while precision is the closeness of the measurements to each other.

Accuracy has two definitions:

More commonly, it is a description of systematic errors, a measure of statistical bias; low accuracy causes a difference between a result and a "true" value. ISO calls this trueness.

Alternatively, ISO defines[1] accuracy as describing a combination of both types of observational error above (random and systematic), so high accuracy requires both high precision and high trueness.

Precision is a description of random errors, a measure of statistical variability.

In simpler terms, given a set of data points from repeated measurements of the same quantity, the set can be said to be accurate if their average is close to the true value of the quantity being measured, while the set can be said to be precise if the values are close to each other. In the first, more common definition of "accuracy" above, the two concepts are independent of each other, so a particular set of data can be said to be either accurate, or precise, or both, or neither.

3 0

3 years ago

A pair of eyeglass frames is made of epoxy plastic. At room temperature (20.0°C), the frames have circular lens holes 2.50 cm in

nignag [31]

Answer:

T₂ = 114 °C

Explanation:

Area or superficial expansion: can be defined as an increase in area, per unit area per degree rise in temperature. It unit is (1/K) or (1/°C).

β = ΔA/(A₁ΔT) ............................................. equation 1

β = 2α ......................................................... equation 2

Area of circle = πr².................................... equation 3

Where β = Area expansivity, α = linear expansivity, ΔA = increase in area = (A₂ - A₁), ΔT = change in temperature, A₁ = initial area, A₂ = Final area r = radius,

from the question, The coefficient of linear expansion for epoxy = 1.3 × 10⁻⁴ °C⁻¹,

∴ Coefficient of area expansion for epoxy = 2 × 1.3 × 10⁻⁴ =

β = 2.6 × 10⁻⁴ °C⁻¹,

Using equation 3 to calculate for area, and taking (π = 3.143)

r₁ = 2.5 cm ∴ A₁ = πr₁² = 3.143 × 2.5² =19.64 cm².

r₂ = 2.53 cm ∴ A₂ = πr₂² = 3.143 × 2.53² =20.12 cm².

ΔA = A₂ - A₁ = 20.12 - 19.64 = 0.48 cm².

Making ΔT the subject of the relation in equation 1.

ΔT = ΔA/(βA₁) ...................................... equation 4

Substituting the values above into equation 4,

ΔT = 0.48/(2.6 × 10⁻⁴ × 19.64)

ΔT = 0.48/(51.064 × 10⁻⁴)

ΔT =( 0.48/51.064) × 10000

ΔT = 0.0094 × 10000 = 94 °C

But, ΔT = T₂ -T₁,

Then, T₂ = ΔT + T₁

Where T₁ = 20 °C, ΔT =94 °C

∴ T₂ = 94 + 20 = 114 °C.

Therefore, temperature at which the frame must be heated if the the lenses 2.53 cm are to be inserted in them = 114 °C

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4 years ago

What type of contraction requires the greatest amount of tension?

mars1129 [50]

Answer:

Isotonic eccentric

Explanation:

First of all, it should be noted that the term contraction has the meaning of joining or shortening. In the field of bodybuilding and workouts with loads, we can define muscle contraction as what happens whenever muscle fibers generate a tension in themselves.

This tension situation occurs in several situations, including when the muscle is shortened, elongated, moving, maintaining the same length or static.

There are different types of muscle contraction, among them we can highlight isotonic contraction, which is divided in turn into concentric and eccentric, isometric, auxotonic and isokinetic contraction.

Isotonic contraction is the most common type of contraction that occurs in most sports or physical activities that we perform in our day to day. Normally the muscular tensions that we exert are usually accompanied by a shortening and lengthening of the muscle fibers of a muscle. In turn, the isotonic contraction is divided into two, concentric and eccentric.

Concentric concentration: is that which happens when a muscle makes a tension capable of overcoming a resistance, producing a shortening and subsequent mobilization of a part of the body overcoming said resistance. For example, when we take a spoon and take it to our mouths to eat, a concentric shortening occurs. Putting examples in the gym on the bench press the movement of raising the bar, is equivalent to the concentric phase.

Eccentric concentration: we can say that it is one in which, given a resistance, we exert a greater tension with the muscle, so that said muscle is lengthened. In the case of the bench press, the eccentric phase is when we lower the bar to the chest.

8 0

3 years ago

3) Using the rating of perceived exertion scale that we

Schach [20]

Answer:

What do you mean

Explanation:

7 0

3 years ago