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3 years ago

Why does a green leaf look green in our eyes

Physics

2 answers:

maria [59]3 years ago

8 0

Answer:

because the leaf absorbs all the other colors except for green. So the leaf reflects the green color which is what we see. that is why a leaf spears to be green.

Explanation:

floor gang aooh sub to pewdiepie

mamaluj [8]3 years ago

3 0

They look green because of the “special pair” of chlorophyll molecules.

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Lilit [14]

Answer:

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6 0

3 years ago

A truck is hauling a 300-kg log out of a ditch using a winch attached to the back of the truck. Knowing the winch applies a cons

torisob [31]

Answer:

0.1 s

Explanation:

The net force on the log is F - f = ma where F = force due to winch = 2850 N, f = kinetic frictional force = μmg where μ = coefficient of kinetic friction between log and ground = 0.45, m = mass of log = 300 kg and g = acceleration due to gravity = 9.8 m/s² and a = acceleration of log

So F - f = ma

F - μmg = ma

F/m - μg = a

So, substituting the values of the variables into the equation, we have

a = F/m - μg

a = 2850 N/300 kg - 0.45 × 9.8 m/s²

a = 9.5 m/s² - 4.41 m/s²

a = 5.09 m/s²

Since acceleration, a = (v - u)/t where u = initial velocity of log = 0 m/s (since it was a rest before being pulled out of the ditch), v = final velocity of log = 0.5 m/s and t = time taken for the log to reach a speed of 0.5 m/s.

So, making t subject of the formula, we have

t = (v - u)/a

substituting the values of the variables into the equation, we have

t = (v - u)/a

t = (0.5 m/s - 0 m/s)/5.09 m/s²

t = 0.5 m/s ÷ 5.09 m/s²

t = 0.098 s

t ≅ 0.1 s

6 0

2 years ago

A wire with a length of 150 m and a radius of 0.15 mm carries a current with a uniform current density of 2.8 x 10^7A/m^2. The c

Mrac [35]

Answer:

The current is 2.0 A.

(A) is correct option.

Explanation:

Given that,

Length = 150 m

Radius = 0.15 mm

Current density $J=2.8\times10^{7}\ A/m^2$

We need to calculate the current

Using formula of current density

$J = \dfrac{I}{A}$

$I=J\timesA$

Where, J = current density

A = area

I = current

Put the value into the formula

$I=2.8\times10^{7}\times\pi\times(0.15\times10^{-3})^2$

$I=1.97=2.0\ A$

Hence, The current is 2.0 A.

7 0

3 years ago

A type of light bulb is labeled having an average lifetime of 1000 hours. It’s reasonable to model the probability of failure of

SashulF [63]

Answer:

$0.2592 \ or \ 25.92\%$

Explanation:

The exponential density function is given as

$f(t)=\left \{ {{0} \atop {ce^{ct}}} \right\\0,t$

$\mu=\frac{1}{c}\\c=\frac{1}{\mu}\\\\=\frac{1}{1000}=0.001\\\\f(t)=0.001e^{-0.001t}$

To find probability that bulb fails with the first 300hrs, we integrate from o to 300:

$P(0\leq X\leq 300)=\int\limits^{300}_0 {f(t)} \, dt\\\\=\int\limits^{300}_0 {0.001e^{-001t}} \, dt\\ =|-e^{-0.001t}| \ 0\leq t\leq 300$

$P(0\leq X\leq 300)=-0.7408+1\\=0.2592$

Hence probability of bulb failing within 300hrs is 25.92% or 0.2592

3 0

3 years ago

A vessel contains 1 mol of O2 and 2mol of He.what is the value of'Cp/Cv ' of the mixture?

BlackZzzverrR [31]

Oxygen is diatomic, so its degree of freedom, (f1)= 5,
also its number of moles, n1= 1

Helium is monoatomic, so its degree of freedom (f2)= 3
and its number of moles given is, n2=2

Now using formula of effective degree of freedom of mixture, (f), we have:

f= (f1n1+f2n2)/(n1+n2)
= (5*1 + 3*2)/ (1+3)
=11/3
Also, from first law of thermodynamics;
U= n Cv. T = nRT(f2)
or, Cv = R. (f/2) (n & T cancel)

We know f=11/6,
substituting the value in above relation, we have:

Cv= R. 11/3*2
= R. 11/6

Also, Cp-Cv = R
or, Cp- R.(11/6)= R
or, Cp= R(11/6 )+1
= 17/6 R

Therefore, Cp/Cv = 17/11

6 0

3 years ago