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3 years ago

The universe could be considered an isolated system because

1 answer:

8 0

a) many people think that no energy or matter exists outside the universe.

An isolated system is defined as a system that does not interact with its surroundings. This is the reason that its total energy and mass remains constant. Moreover, total momentum in a system is conserved for collisions occurring in isolated systems.

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The electromagnetic wave that delivers a cellular phone callto

spin [16.1K]

Answer:

$E=2.41\cdot 10^{-5} J$

Explanation:

The intensity of an electromagnetic wave can be expressed in terms of the magnetic field using the next relationship:

$I_{average}=\frac{cB_{0}^{2}}{2\mu_{0}}$ (1)

c is the speed of light (3*10⁸ m/s)
μ₀ is the permeability of free space (in vacuum ) (1.26*10⁻⁶ N/A²)
B₀ is the magnetic field

$I_{average}=\frac{3\cdot 10^{8}(1.5\cdot 10^{-10})^{2}}{2\cdot 1.26\cdot 10^{-6}}$

$I_{average}=2.68\cdot 10^{-6} W/m^{2}$

Now, let's define the relationship between power (P) and average intensity (I).

$I_{average}=\frac{P}{A}$

P is the power
A is the area crossed

So we can calculate the power.

$P=I_{average}\cdot A=2.68\cdot 10^{-6}\cdot 0.20=5.37\cdot 10^{-7} W$

Finally, energy is the product of P times time, so:

$E=P\cdot t=5.37\cdot 10^{-7} \cdot 45=2.41\cdot 10^{-5} J$

I hope it helps you!

5 0

3 years ago

The x vector component of a displacement vector has a magnitude of 86.2 m and points along the negative x axis. The y vector com

Flauer [41]

Answer:

(a) Magnitude of Vector = 207.73 m

(b) Direction = 65.48°

Explanation:

(a)

The formula to find out the magnitude of a resultant vector with the help of its x and y components is given as follows:

$Magnitude\ of\ Vector = \sqrt{d_{x}^{2} + d_{y}^{2}} = \sqrt{(86.2\ m)^{2} + (189\ m)^{2}}\\\\$

Magnitude of Vector = 207.73 m

(b)

For the direction of the vector we have the formula:

$Direction = tan^{-1}(\frac{y}{x})\\\\Direction = tan^{-1}(\frac{189\ m}{86.2\ m})\\\\$

Direction = 65.48°

4 0

3 years ago

A block of aluminium of density 7900 kg/m3 has a volume of 250 cm. Find the mass of the block.

pashok25 [27]

Answer:

mass of block=2.7 gm

Explanation:

concept: Density=mass/volume

given:ρ=2700 kg/m^3 and v=250 cm^3 (in cm^3 not in m^3)

=> v= convert cm^3 to m^3

there fore= 1 cm^3=1 cm*1 cm*1 cm

i.e 1 cm^3=1/100*1/00*1/100 m^3 => 1 cm^3=1/1000000 m^3

ρ=m/v

=>mass=ρ*volume

=>mass=2700*1/10^-6

=>mass=2.7*10^-3 kg =>2.7 gm

8 0

3 years ago

Xenon hexafluoride was one of the first noble gas compounds synthesized. The solid reacts rapidly with the silicon dioxide in gl

Oxana [17]

Answer:

0,93 atm

Explanation:

For this we will use PV = nRT

P is what we want to find

V = 1 L

n = $\frac{8.53}{223.23}$ = 0,038 moles

R = 0,082 $\frac{L atm}{K mole}$

T = 25°C = 298,15 K

P * 1 = 0,038 *0,082 * 298,15

P = 0,93 atm

5 0

3 years ago

(BRAINLIEST) Question: Name 2 waves that you use in your everyday life.

Archy [21]

-- Radio waves. (To hear the weather while I'm waking up.)

-- Light waves. (To see where the dog is so I don't step on him.)

-- Infrared waves. (To make my toast for breakfast.)

-- Microwaves. (To heat my oatmeal for breakfast. Also when I go in to my job as a microwave communications engineer.)

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4 years ago