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mezya [45]
4 years ago
11

Why is air a pure substance?

Physics
2 answers:
cricket20 [7]4 years ago
7 0

Answer:

Air isn't considered a pure substance

Explanation:

Because there is no one single chemical element of compound that forms air. Air is a mixture of various purechemical substances, most of which exist in the gaseous state.

Pani-rosa [81]4 years ago
3 0

Answer:It isn’t

Explanation:

Air isn't considered a pure substance because there is no one single chemical element of compound that forms air. Air is a mixture of various pure chemical substances, most of which exist in the gaseous state.

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True or False: Solids always have a higher density than liquids and gases.
yulyashka [42]

Answer:

TRUE THE ANSWER IS TRUE

8 0
3 years ago
Read 2 more answers
A person of mass 55 kg swings on a rope length 4 m from rest (when the rope makes an angle of 30 degrees with the vertical) and
vovangra [49]

Answer:

θ = 19.66°

Explanation:

To determine the angle that the rope makes with the vertical for the two people, you first take into account the potential energy of the first person before he swings on the rope:

U=mgh

h: distance to the ground

g: gravitational acceleration = 9.8m/s^2

m: mass of the first person = 55 kg

In the image attache below you can notice that the height h is:

h=4-4cos(30\°)=0.53m

Then, the potential energy is:

U=(55kg)(9.8m/s^2)(0.53m)=285.67J

When the first person picks up the second person (when the rope is exactly vertical), all the potential energy becomes kinetic energy. Next, when both people reaches the maximum height h' the energy must be equal to the initial potential energy of the first person:

U'=(m_1+m_2)gh'=285.67\ J

From the previous equation you can get h':

h'=\frac{285.67J}{(55kg+70kg)(9.8m/s^2)}=0.2332m

Finally, you obtain the angle between the rope at the height h,' and the vertical, by calculating the following:

h'=4-4cos(\theta)\\\\\theta=cos^{-1}(\frac{4-h'}{4})=cos^{-1}(\frac{4-0.2332}{4})=19.66\°

hence, the angle between the rope and the vertical, when the two people are in the rope is 19.66°

8 0
3 years ago
An empty rubber balloon has a mass of 0.0120 kg. The balloon is filled with helium at 0°C, 1 atm pressure, and a density of 0.17
Anuta_ua [19.1K]

Answer:

a) F_b = 6.62 N

b) F_net = 5.583 N

Explanation:

Given:

- Conditions of He gas:  T = 0 C , P = 1 atm , ρ = 0.179 kg/m^3

- The mass of balloon m = 0.012 kg

- The radius of balloon r = 0.5 m

Find:

a)What is the magnitude of the buoyant force acting on the balloon?

b)What is the magnitude of the net force acting on the balloon?

Solution:

- The buoyant force F_b acting on the balloon is equal to the weight of the air it displaces.The mass of the displaced air ρ*V is the volume of the balloon times the density of the. Multiplying that by acceleration due to gravity gives its weight.

                                 F_b = ρ*V*g

                                 F_b = 4*ρ*g*pi*r^3 / 3

                                 F_b = 4*1.29*9.81*pi*.5^3 / 3

                                 F_b = 6.62 N

- The net force will be the difference between the balloon’s weight and the buoyant force. The weight of the balloon is the density of the helium times the volume of the balloon added to the mass of the empty balloon.

                                 F_g = ρ*V*g + m*g

                                 F_g = 4*ρ*g*pi*r^3 / 3 + 0.012*9.81

                                 F_g = 4*0.179*9.81*pi*.5^3 / 3 + 0.012*9.81

                                 F_g = 1.037 N

- The net force is the difference between weight and buoyant force

                                F_net = F_g - F_b

                                F_net = 6.62 - 1.037

                                F_net = 5.583 N

7 0
4 years ago
58.54
Lilit [14]

Answer:

6m/s^2

Explanation:

at=Vf-Vi

a=? a(5)=65-35

t=5 a(5)=30

Vi=35 a(5)/5=30/5

Vf=65 a=6m/s^2

7 0
3 years ago
A water molecule perpendicular to an electric field has 1.40×10−21 J more potential energy than a water molecule aligned with th
vesna_86 [32]

Answer:

The strength of the electric field is 2.258 x 10⁸ N/C

Explanation:

Potential energy = -p*ECosθ

where;

d is the dipole moment

E is the electric field  

θ is the angle of inclination

→When the water molecules is perpendicular to the field, θ =90° and potential energy = p*ECosθ = d*ECos0 = 0

Total potential energy = 0 + 1.40×10⁻²¹J, since it is 1.40×10⁻²¹J more

→When the water molecules is aligned to the field, θ =0°

potential energy = -p*ECosθ

dipole moment, p = 6.2×10⁻³⁰Cm

                            = -(6.2×10⁻³⁰)*(E) Cos0

0 + 1.40×10⁻²¹ J = -(6.2×10⁻³⁰)*(E),

E = (1.40×10⁻²¹ J)/(6.2×10⁻³⁰)

E = 2.258 x 10⁸ N/C

Therefore, the strength of the electric field is 2.258 x 10⁸ N/C

3 0
4 years ago
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