Which best explains why a wood-burning fireplace represents an open system?

A conducting sphere 45 cm in diameter carries an excess of charge, and no other charges are present. You measure the potential o

uysha [10]

Answer:

The excess charge is $Q = 3.5 *10^{-7} \ C$

Explanation:

From the question we are told that

The diameter is $d = 45 \ cm = 0.45 \ m$

The potential of the surface is $V = 14 \ kV = 14 *10^{3} \ V$

The radius of the sphere is

$r = \frac{d}{2}$

substituting values

$r = \frac{0.45}{2}$

$r = 0.225 \ m$

The potential on the surface is mathematically represented as

$V = \frac{k * Q }{r }$

Where k is coulomb's constant with value $k = 9*10^{9} \ kg\cdot m^3\cdot s^{-4} \cdot A^{-2}.$

given from the question that there is no other charge the Q is the excess charge

Thus

$Q = \frac{V* r}{ k}$

substituting values

$Q = \frac{14 *10^{3} 0.225}{ 9*10^9}$

$Q = 3.5 *10^{-7} \ C$

7 0

4 years ago

A block of mass 3.20 kg is placed against a horizontal spring of constant k = 865 N/m and pushed so the spring compresses by 0.0

Aliun [14]

Answer:

a) The initial elastic potential energy of the block-spring system is 28.113 joules.

b) The final speed of the block is approximately 4.192 meters per second.

Explanation:

a) By applying Hooke's law and definition of work, we define the elastic potential energy ( $U_{g}$ ), measured in joules, by the following formula:

$U_{g} = \frac{1}{2}\cdot k\cdot x^{2}$ (1)

Where:

$k$ - Spring constant, measured in newtons per meter.

$x$ - Deformation of the spring, measured in meters.

If we know that $k = 865\,\frac{N}{m}$ and $x = 0.065\,m$ , then the elastic potential energy is:

$U_{g} = \frac{1}{2}\cdot \left(865\,\frac{N}{m} \right) \cdot (0.065\,m)$

$U_{g} = 28.113\,J$

The initial elastic potential energy of the block-spring system is 28.113 joules.

b) According to the Principle of Energy Conservation, the initial elastic potential energy of the block-spring system becomes into translational kinetic energy, that is:

$U_{g} = \frac{1}{2}\cdot m\cdot v^{2}$ (2)

Where:

$m$ - Mass, measured in kilograms.

$v$ - Final speed, measured in meters per second.

Then, the final speed is cleared:

$v = \sqrt{\frac{2\cdot U_{g}}{m} }$

If we know that $U_{g} = 28.113\,J$ and $m = 3.20\,kg$ , then the final speed of the block is:

$v = \sqrt{\frac{2\cdot (28.113\,J)}{3.20\,kg} }$

$v \approx 4.192\,\frac{m}{s}$

The final speed of the block is approximately 4.192 meters per second.

3 0

3 years ago

When an object with a height of 0.10 meter is placed at a distance of 0.20 meter from a convex

seraphim [82]

Answer:

h = 0.1 m = 10 cm

u = 0.2 m = 20 cm

v = 0.06 m = 6 cm

m = h'/h = v/u

h'/10 = 6/20

h' = 60/20 = 3 cm

Therefore image height = 3 cm(0.03 m)

Hope this helps!

8 0

3 years ago

Read 2 more answers

Some fuel cells are powered by hydrogen. Scientists are looking into the decomposition of water (H2O) to make hydrogen fuel with

mr_godi [17]

A challenge scientists face with this process is the use of ultrathin iron oxide, to pull protons off water and produce hydrogen gas, which itself is a poor electrical conductor.

5 0

3 years ago

Read 2 more answers

A centrifugal pump is operating at a flow rate of 1 m3/s and a head of 20 m. If the specific weight of water is 9800 N/m3 and th

tamaranim1 [39]

Answer:

<em>The power required by the pump is nearly 230.588 kW</em>

Explanation:

Flow rate of the pump Q = 1 m^3/s

the head flow H = 20 m

specific weight of water γ = 9800 N/m^3

efficiency of the pump η = 85%

First note that specific gravity of water is the product of the density of water and acceleration due to gravity.

γ = ρg

where ρ is density. For water its value is 1000 kg/m^3

g is the acceleration due to gravity = 9.81 m/s^2

The power to lift this water at this rate will be gotten from the equation

P = ρgQH

but ρg = γ

therefore,

P = γQH

imputing values, we'll have

P = 9800 x 1 x 20 = 196000 W

But the centrifugal pump that will be used will only be able to lift this amount of water after the efficiency factor has been considered. The power of pump needed must be greater than this power.

we can say that

196000 W is 85% of the power of the pump power needed, therefore

196000 = 85% of $P_{p}$

where $P_{p}$ is the power of the pump needed

85% = 0.85

196000 = 0.85 $P_{p}$

$P_{p}$ = 196000/0.85 = 230588.24 W

<em>Pump power = 230.588 kW</em>

3 0

4 years ago