Factor each expression.<br>a. d2 + 8d + 7

Which of the following is produced as a result of photosynthesis

kenny6666 [7]

I think the answer is D but i could be wrong

3 0

2 years ago

A baseball of radius r = 5.2 cm is at room temperature T = 20.8 C. The baseball has emissivity of ε = 0.86 and the Stefan-Boltzm

Marrrta [24]

Answer:

$P = 12.37 \frac{J}{s} = 12.37 Watts$

Explanation:

Previous concepts

The Thermal radiation is one of "3 mechanisms who allows to bodies exchange energy".

The thermal radiation formula is given by:

$\frac{P}{A} = \epsilon \sigma T^4$

Where $\sigma = 5.67 x10^{-8} \frac{J}{sm^2 K^4}$

If we solve for P we got:

$P = A \epsilon \sigma T^4$

Since we have a baseball ball considered as a sphere the superficial area is given by:

$A = 4\pi r^2$

Solution to the problem

And if we replace this into our equation of P we got:

$P = (4\pi r^2) \epsilon \sigma T^4$

And we can reorder this like that:

$P = 4 \epsilon \pi \sigma r^2 T^4$

We can convert the radius to meters and we got:

$r= 5.2 cm*\frac{1m}{100 cm}=0.052 m$

Now we can convert the temperature to Kelvin and we got:

$T = 20.8 +273.15 = 293.95 K$

$\epsilon = 0.86$ the emissivity given

And now we can replace into the formula for P and we got:

$P = 4*0.86*\pi *(5.67x10^{-8} \frac{J}{s m^2 K^4}) (0.052m)^2 (293.95 K)^4$

$P = 12.37 \frac{J}{s} = 12.37 Watts$

6 0

2 years ago

A proton moving in the positive x direction with a speed of 8.9 105 m/s experiences zero magnetic force. When it moves in the po

solniwko [45]

Answer:

The magnitude of magnetic field is 1.19 T and its direction magnetic is in negative x direction.

Explanation:

Given that,

Speed of a proton, $v=8.9\times 10^5\ m/s$ (due +x direction)

When it moves in the positive y direction it experiences a force of, $F=1.7\times 10^{-13}\ N$ (due positive z direction)

We need to find the magnitude and direction of the magnetic field. The magnetic force is given by :

$F=q(v\times B)\\\\B=\dfrac{F}{qv}\\\\B=\dfrac{1.7\times 10^{-13}}{1.6\times 10^{-19}\times 8.9\times 10^5}\\\\B=1.19\ T$

For direction :

$F=q(v\times B)\\\\k=(+q)(j\times B)\\\\B=-i$

So, the magnitude of magnetic field is 1.19 T and its direction magnetic is in negative x direction.

4 0

2 years ago

According to current evidence, what happens when gays or lesbians rear a child?

Lena [83]

Answer: The answer is A.

Explanation:

Just because u have gay parents doesnt mean theyre bad lol XD

5 0

1 year ago

A helicopter lifts a 81 kg astronaut 19 m vertically from the ocean by means of a cable. The acceleration of the astronaut is g/

nexus9112 [7]

Answer:

a) The work done on the astronaut by the force from the helicopter is $W_{h}=16087.68\ J$ .

b) The work done on the astronaut by the gravitational force is $W_{g}=-15082.2\ J$ .

Explanation:

We are told that the mass of the astronaut is $m=81\ kg$ , the displacement is $\Delta x=19\ m$ , the acceleration of the astronaut is $|\vec{a}|=\frac{g}{15}$ and the acceleration of gravity is $g=9.8\ \frac{m}{s^{2}}$ .

We suppose that in the vertical direction the force from the helicopter $F_{h}$ is upwards and the gravitational force $F_{g}$ is downwards. From the sum of forces we can get the value of $F_{h}$ :

$F_{h}-F_{g}=m.a$

$F_{h}-mg=m.\frac{g}{15}$

$F_{h}=mg(1+\frac{1}{15})$

$F_{h}=(\frac{16}{15}).81\ kg.\ 9.8\ \frac{m}{s^{2}}\ \Longrightarrow\ F_{h}=846.72\ N$

We define work as the product of the force, the displacement of the body and the cosine of the angle $\theta$ between the direction of the force and the displacement of the body: