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3 years ago

PLZ HELP!!!!

2 answers:

4 0

<span>First blank: B) Cutting down trees instead of growing trees
Cutting down trees means less plants that are photosynthesizing and consuming CO2 from the atmosphere.

Second blank: </span><span>D) Using clean energy sources instead of fossil fuels
Clean energy sources have little to no CO2 emissions. On the other hand, fossil fuels, when burned/combusted release large amounts of CO2 into the atmosphere.</span>

ratelena [41]3 years ago

4 0

the answer is b and d

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A wheel is rotating freely at angular speed 660 rev/min on a shaft whose rotational inertia is negligible. A second wheel, initi

sweet-ann [11.9K]

Answer:

(a) 110 rev/ min

(b) 5/6

Explanation:

As per the conservation of linear momentum,

L ( initial ) = L ( final )

I' ω' = ( I' + I'' ) ωf

I' is the rotational inertia of first wheel and I'' is the rotational inertia of second wheel which is at rest.

(a)

So, ωf = I' ω' / ( I' + I'' )

As I'' = 5I'

ωf = I' ω' / ( I' + 5I' )

ωf = ω'/ 6

now we know ω' = 660 rev / min

therefore ωf = 660/6

= 110 rev/ min

(b)

Initial kinetic energy will be K'

K' = I'ω'² / 2

and final K.E. will be K'' = ( I' + I'' )ωf² / 2

K'' = ( I' + 5I' ) (ω'/ 6)²/ 2

K'' = 6I' ω'²/72

K'' = I' ω'²/ 12

therefore the fraction lost is

ΔK/K' = ( K' - K'' ) / K'

= {( I'ω'² / 2) - (I' ω'²/ 12)} / ( I'ω'² / 2)

= 5/6

6 0

4 years ago

Calculate the height from from which a body is released from rest if its velocity just before hitting the ground is30m\s

Kamila [148]

Answer:

height = 45 m

Explanation:

Initial velocity = 0 m/s

Final velocity = 30 m/s

Acceleration due to gravity = +10m/s^2 ( because ball is going down )

Using the eqn of motion

${v}^{2} - {u}^{2} = 2gh$

where v= final velocity ; u = initial velocity ; g = acceleration due to gravity ; h = height

So,

${30}^{2} - {0}^{2} = 2 \times 10 \times h$

$= > 20h = 900$

$= > h = \frac{900}{20} = 45$

5 0

3 years ago

Which of the following statements is true regarding the use of refrigerants?

Damm [24]

B.

Refrigerants should be handled using approved equipment only.

5 0

3 years ago

Read 2 more answers

I need help now please help me

alexandr1967 [171]

The correct answer is C. Plug in x and y value for answers to see if they work. For example, 9/3 = 3. So C is the answer.

8 0

4 years ago

A 0.12 g honeybee acquires a charge of +24pC while flying. The earth's electric field near the surface is typically 100 N/C, dow

shusha [124]

Answer:

150000000

$\dfrac{F_e}{F_g}=0.00000203873598369$

49050000 N/C

Explanation:

q = Charge = 24 pC

m = Mass of honeybee = 0.12 g

E = Electric field = 100 N/C

g = Acceleration due to gravity = 9.81 m/s²

$1\ C=6.25\times 10^{18}\ electrons$

Number electrons is

$n=24\times 10^{-12}\times 6.25\times 10^{18}\\\Rightarrow n=150000000$

The number of electrons added or removed was 150000000

Force is given by

$F_e=Eq\\\Rightarrow F_e=100\times 24\times 10^{-12}\\\Rightarrow F_e=2.4\times 10^{-9}\ N$

The ratio is

$\dfrac{F_e}{F_g}=\dfrac{2.4\times 10^{-9}}{0.12\times 10^{-3}\times 9.81}\\\Rightarrow \dfrac{F_e}{F_g}=0.00000203873598369$

The ratio is $\dfrac{F_e}{F_g}=0.00000203873598369$

Balancing the forces we get

$Eq=mg\\\Rightarrow E=\dfrac{mg}{q}\\\Rightarrow E=\dfrac{0.12\times 10^{-3}\times 9.81}{24\times 10^{-12}}\\\Rightarrow E=49050000\ N/C$

The electric field required is 49050000 N/C

4 0

4 years ago