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2 years ago

Two charges with a certain distance apart have an electrostatic force of 400 N acting

1 answer:

3 0

As the charges’ distance increase, there is a weaker force of attraction between them hence the electrostatic force decreases as distance increases. It increase by 4 (times 4) so the force will decrease by 4 making the answer

=A (400 divided by 4 = 100)

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A system proposed by the U.S. Navy for underwater submarine communication, called ELF (for extremely low frequency), operates wi

kow [346]

Answer

Wavelength= 30*20^8/30=10^7m

Explanation:

Velocity = frequency *wavelength

We're frequency=30HZ

Velocity of light= 3*10^8m/s

Wavelength= 30*20^8/30=10^7m

Explanation:

7 0

3 years ago

Read 2 more answers

Determine the power that needs to besupplied by the fanifthe desired velocity is 0.05 m3/s and the cross-sectional area is 20 cm

Mariulka [41]

Answer:

A fan with an energy efficiency of 30 % would need 62.5 watts to bring a desired volume flow of 0.05 cubic meters per second through a cross-sectional area of 20 square centimeters.

Explanation:

Complete statement is: <em>Determine the power that needs to besupplied by the fan if the desired velocity is 0.05 cubic meters per second and the cross-sectional area is 20 square centimeters.</em>

From Thermodynamics and Fluid Mechanics we know that fans are devices that work at steady state which accelerate gases (i.e. air) with no changes in pressure. In this case, mechanical rotation energy is transformed into kinetic energy. If we include losses due to mechanical friction, the Principle of Energy Conservation presents the following equation:

$\eta\cdot \dot W = \dot K$

$\dot W = \frac{\dot K}{\eta}$ (Eq. 1)

Where:

$\eta$ - Efficiency of fan, dimensionless.

$\dot W$ - Electric power supplied fan, measured in watts.

$\dot K$ - Rate of change of kinetic energy of air in time, measured in watts.

From definition of kinetic energy, the equation above is now expanded:

$\dot W = \frac{\rho_{a}\cdot \dot V}{2\cdot \eta}\cdot \left(\frac{\dot V}{A_{s}} \right)^{2}$ (Eq. 2)

Where:

$\rho_{a}$ - Density of air, measured in kilograms per cubic meter.

$\dot V$ - Volume flow, measured in cubic meters per second.

$A_{s}$ - Cross-sectional area of fan, measured in square meters.

If we know that $\rho_{a} = 1.20\,\frac{kg}{m^{3}}$ , $\dot V = 0.05\,\frac{m^{3}}{s}$ , $\eta = 0.3$ and $A_{s} = 20\times 10^{-4}\,m^{2}$ , the power needed to be supplied by the fan is:

$\dot K = \left[\frac{\left(1.20\,\frac{kg}{m^{3}} \right)\cdot \left(0.05\,\frac{m^{3}}{s} \right)}{2\cdot (0.3)} \right]\cdot \left(\frac{0.05\,\frac{m^{3}}{s} }{20\times 10^{-4}\,m^{2}} \right)^{2}$

$\dot K = 62.5\,W$

A fan with an energy efficiency of 30 % would need 62.5 watts to bring a desired volume flow of 0.05 cubic meters per second through a cross-sectional area of 20 square centimeters.

5 0

3 years ago

The magnetic field in a solenoid is . A circular wire of radius 8 cm is concentric with a solenoid of radius 2 cm and length d =

defon

Answer:

6.03 mV

Explanation:

length of solenoid, L = 2 m, N = 12000, di/dt = 40 A/s,

Magnetic field due to solenoid

B = μ0 n i = μ0 N i / L

dB/dt = μ0 N / L x di / dt

dB /dt = (4 x 3.14 x 10^-7 x 12000 x 40) / 2 = 0.3 T/s

Induced emf, e = rate of change of magnetic flux

e = dΦ / dt = A x dB / dt

e = 3.14 x 0.08 x 0.08 x 0.3 = 6.03 x 10^-3 V = 6.03 mV

7 0

3 years ago

A beam of protons enter the electric field of magnitude E = 0.5 N/C between a pair of parallel plates. There is a magnetic field

HACTEHA [7]

Answer:

0.217 m/s

Explanation:

The protons in the beam passes undeflected when the electric force is equal to the magnetic force:

qE = qvB

where

q is the proton's charge

E is the magnitude of the electric field

v is the speed of the protons

B is the magnitude of the magnetic field

Re-arranging the equation,

$v=\frac{E}{B}$

And by substituting

E = 0.5 N/C

B = 2.3 T

We find

$v=\frac{0.5}{2.3}=0.217 m/s$

3 0

3 years ago

A physics professor demonstrates the Doppler effect by tying a 600 Hz sound generator to a 1.0-m-long rope and whirling it aroun

VARVARA [1.3K]

Answer:

(a) f= 622.79 Hz

(b) f= 578.82 Hz

Explanation:

Given Data

Frequency= 600 Hz

Distance=1.0 m

n=120 rpm

Temperature =20 degree

Before solve this problem we need to find The sound generator moves on a circular with tangential velocity

Speed of sound is given by

c = √(γ·R·T/M) ............in an ideal gas

where γ heat capacity ratio

R universal gas constant

T absolute temperature

M molar mass

The speed of sound at 20°C is

c = √(1.40 ×8.314472J/molK ×293.15K / 0.0289645kg/mol)

c= 343.24m/s

The sound moves on a circular with tangential velocity

vt = ω·r.................where ω=2·π·n

vt= 2·π·n·r

vt= 2·π · 120min⁻¹ · 1m

vt= 753.6 m/min

convert m/min to m/sec

vt= 12.56 m/s

Part A

For maximum frequency is observed

v = vt

f = f₀/(1 - vt/c )

f= 600Hz / (1 - (12.56m/s / 343.24m/s) )

f= 622.789 Hz

Part B

For minimum frequency is observed

v = -vt

f = f₀/(1 + vt/c )

f= 600Hz / (1 + (12.56m/s / 343.24m/s) )

f= 578.82 Hz

3 0

3 years ago