Which statement correctly identifies a difference between the function of most arteries and veins?

Light is shining perpendicularly on the surface of the earth with an intensity of 680 W/m^2. Assuming that all the photons in th

andrew11 [14]

Answer:

3.066×10^21 photons/(s.m^2)

Explanation:

The power per area is:

Power/A = (# of photons /t /A)×(energy / photon)

E/photons = h×c/(λ)

photons /t /A = (Power/A)×λ /(h×c)

photons /t /A = (P/A)×λ/(hc)

photons /t /A = (680)×(678×10^-9)/(6.63×10^-34)×(3×10^-8)

= 3.066×10^21

Therefore, the number of photons per second per square meter 3.066×10^21 photons/(s.m^2).

4 0

3 years ago

A particle moving along the x-axis has its velocity described by the function vx =2t2m/s, where t is in s. its initial position

Nesterboy [21]

The position of the object at time t =2.0 s is 6.4 m.

Velocity vₓ of a body is the rate at which the position x of the object changes with time.

Therefore,

$v_x= \frac{dx}{dt}$

Write an equation for x.

$dx=v_xdt\\ x=\int v_xdt$

Substitute the equation for vₓ =2t² in the integral.

$x=\int v_xdt\\ =\int2t^2dt\\ =\frac{2t^3}{3} +C$

Here, the constant of integration is C and it is determined by applying initial conditions.

When t =0, x = 1. 1m

$x= \frac{2t^3}{3} +C\\ x_0=1.1\\ x= (\frac{2t^3}{3} +1.1)m$

Substitute 2.0s for t.

$x= (\frac{2t^3}{3} +1.1)m\\ =\frac{2(2.0)^3}{3} +1.1\\ =6.43 m$

The position of the particle at t =2.0 s is 6.4m

5 0

2 years ago

The human activities in two locations are described below:

Bogdan [553]

Air pollution level is higher in Location B, because poisonous fumes are produced when coal burns.

5 0

3 years ago

Read 2 more answers

Earth can be modeled with five layers based on the strengths and physical properties of the materials in them. Put the layers in

andre [41]

Answer:

Crust, Upper mantle, mantle, outer core, inner core

Explanation:

The Earth's layers have been clasified in 5 according to the materials that conform them, theri physical properties, strengths and also their state of matter. We all know how the outer layer of the Earth looks like, but if we start to dig a huge hole we are going to see different types por materials due to a change in pressure, temperature, and other factors. At the very center of the Earth there's what's called "core". The core is liquid and at extremely high temperatures. This is because of the enormous amount of pressure the rest of the Earth is putting it under. So, if we list the different layers of the Earth according to the materials they are made of, from the Earth's surface to the core, the answer is:

1) Crust (surface)

2) Upper Mantle

3) Mantle

4) Outer core

5) Inner core

In some books you may find a layer called Lithosphere. Tis layer consists not only of the crust, but also it contains the transition zone between the upper mantle and the crust.

4 0

3 years ago

An automobile traveling 95 km/h overtakes a 1.30-km-long train traveling in the same direction on a track parallel to the road.

SOVA2 [1]

Answer:

Same direction: t=234s; d=6.175Km

Opposite direction: t=27.53s; d=0.73Km

Explanation:

If the automobile and the train are traveling in the same direction, then the automobile speed relative to the train will be $v_{AT}=v_A-v_T$ (the train must see the car advancing at a lower speed), where $v_A$ is the speed of the automobile and $v_T$ the speed of the train.

So we have $v_{AT}=(95km/h)-(75Km/h)=20Km/h$ .

So the train (anyone in fact) will watch the automobile trying to cover the lenght of the train L at that relative speed. The time required to do this will be:

$t = \frac{L}{v_{AT}} = \frac{1.3Km}{20Km/h} = 0.065h=234s$

And in that time the car would have traveled (relative to the ground):

$d=v_At=(95Km/h)(0.065h)=6.175Km$

If they are traveling in opposite directions, we have to do all the same but using $v_{AT}=v_A+v_T$ (the train must see the car advancing at a faster speed), so repeating the process:

$v_{AT}=(95km/h)+(75Km/h)=170Km/h$

$t = \frac{L}{v_{AT}} = \frac{1.3Km}{170Km/h} = 0.00765h=27.53s$

$d=v_At=(95Km/h)(0.00765h)=0.73Km$

5 0

2 years ago