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butalik [34]
3 years ago
13

Which of the following describes the efficiency of real machines?

Physics
2 answers:
Mariulka [41]3 years ago
4 0

Are you sure! Becuase I dont want to get this one wrong!



Leokris [45]3 years ago
3 0
Choice-B is the true one.
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The drag force pushes opposite your motion as you ride a bicycle. If you double your speed, what happens to the drag force?
timurjin [86]

Answer: The drag force goes up by a factor of 4

Explanation:

The <u>Drag Force</u> equation is:

F_{D}=\frac{1}{2}C_{D}\rho A_{D}V^{2} (1)

Where:

F_{D} is the Drag Force

C_{D} is the Drag coefficient, which depends on the material

\rho is the density of the fluid where the bicycle is moving (<u>air in this case) </u>

A_{D} is the transversal area of the body or object

V the bicycle's velocity

Now, if we assume C_{D}, \rho and A_{D} do not change, we can rewrite (1) as:

F_{D}=C.V^{2} (2)

Where C groups all these coefficients.

So, if we have a new velocity V_{n} , which is the double of the former velocity:

V_{n}=2V (3)

Equation (2) is written as:

F_{D}=C.V_{n}^{2}=C.(2V)^{2}

F_{D}=4CV^{2} (4)

Comparing (2) and (4) we can conclude<u> the Drag force is four times greater when the speed is doubled.</u>

7 0
3 years ago
The lightest car in the world was built in London and had a mass of less than 10 kg. it's maximum speed was 25.0 km/h. Suppose t
Softa [21]
25km/h = 6.94 m/s
suvat
s=16
u=6.94
v=0
a=a
v^2=u^2+2as
(v^2-u^2)/2s = a =1.5ms^-2
6 0
3 years ago
What type of motion does the galaxy go through
Mariana [72]

Well, it depends. Your latitude on Earth--that is, how close you are to the equator--and the time of year make a difference. I'll explain why. Your motion is made up of four pieces: the rotation of the Earth on its axis, the motion of the Earth around the Sun, the Sun's orbit about the center of the galaxy, and the motion of the whole galaxy.


8 0
3 years ago
What are non-metals?<br>explain briefly​
aliya0001 [1]

Answer:

In chemistry, a nonmetal is a chemical element that is mechanically weak in its most stable form, brittle if solid, and usually gains or shares electrons in chemical reactions. There is no universal agreement on which elements are nonmetals; the numbers generally range from fourteen to twenty-three, depending on the criterion or criteria of interest.

3 0
2 years ago
Read 2 more answers
Sapting Leng You have a string with a mass of 13.7 q. You stretch the string with a force of 8.39 N, giving it a length of 1.87
marshall27 [118]

Answer:

a)  \lambda=0.935\ \textup{m}

b) f=36.19\approx 36\ \textup{Hz}

Explanation:

Given:

String vibrates transversely fourth dynamic, thus n = 4

mass of the string, m = 13.7 g = 13.7 × 10⁻¹³ kg

Tension in the string, T = 8.39 N

Length of the string, L = 1.87 m

a) we know

L= n\frac{\lambda}{2}

where,

\lambda = wavelength

on substituting the values, we get

1.87= 4\times \frac{\lambda}{2}

or

\lambda=0.935\ \textup{m}

b) Speed of the wave (v) in the string is given as:

v =f\lambda

also,

v=\sqrt\frac{T}{(\frac{m}{L})}

equating both the formula for 'v' we get,

f\lambda=\sqrt\frac{T}{(\frac{m}{L})}

on substituting the values, we get

f\times 0.935=\sqrt\frac{8.39}{(\frac{13.7\times 10^{3}}{1.87})}

or

f=\frac{33.84}{0.935}

or

f=36.19\approx 36\ \textup{Hz}

5 0
3 years ago
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