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3 years ago

The commutator of a universal motor connects each armature coil to

Physics

2 answers:

DIA [1.3K]3 years ago

5 0

Answer:

a. the rotor

Explanation:

A commutator is a rotary electric switch that periodically changes the direction of the current between the rotor and the external circuit. In a motor provides energy to the rotor. It consists of a cylinder composed of multiple metal contact segments on the rotor.

tatiyna3 years ago

4 0

The answer is a. the rotor

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Water at 20°C flows by gravity through a smooth pipe from one reservoir to a lower one. The elevation difference is 60 m. The pi

Serga [27]

Answer:

Flow Rate = 80 m^3 /hours (Rounded to the nearest whole number)

Explanation:

Given

Hf = head loss
f = friction factor
L = Length of the pipe = 360 m
V = Flow velocity, m/s
D = Pipe diameter = 0.12 m
g = Gravitational acceleration, m/s^2
Re = Reynolds's Number
rho = Density =998 kg/m^3
μ = Viscosity = 0.001 kg/m-s
Z = Elevation Difference = 60 m

Calculations

Moody friction loss in the pipe = Hf = (f*L*V^2)/(2*D*g)

The energy equation for this system will be,

Hp = Z + Hf

The other three equations to solve the above equations are:

Re = (rho*V*D)/ μ

Flow Rate, Q = V*(pi/4)*D^2

Power = 15000 W = rho*g*Q*Hp

1/f^0.5 = 2*log ((Re*f^0.5)/2.51)

We can iterate the 5 equations to find f and solve them to find the values of:

Re = 235000

f = 0.015

V = 1.97 m/s

And use them to find the flow rate,

Q = V*(pi/4)*D^2

Q = (1.97)*(pi/4)*(0.12)^2 = 0.022 m^3/s = 80 m^3 /hours

7 0

3 years ago

A person yells across a canyon and hears an echo 2.5 seconds later. The air temperature is 21°C. How far away is the canyon wall

Alchen [17]

Answer: The canyon wall is 850 m away from the person

Explanation:

Well, the speed of sound $V$ in air at $21 \° C$ is defined as $343.60 m/s$ , this can be calculated by the following equation:

$V=\sqrt{\frac{\gamma R T}{M}}$ (1)

Where:

$\gamma=1.4$ is the Heat capacity ratio for air

$R=8.314 J/mol.K$ is the Universal Gas constant

$T=21 \° C+273.15=294.15 K$ is the temperature in Kelvin

$M=0.029 kg/mol$ is the air molar mass

$V=\sqrt{\frac{(1.4)(8.314 J/mol.K)(294.15 K)}{0.029 kg/mol}}$

$V=343.60 m/s$ (2)

Now that we know the speed of sound, we can use the following equation to find the distance between the person and the canyon wall:

$V=\frac{d}{t}$ (3)

Where:

$d$ is the distance between the person and the canyon wall

$t=2.5 s$ is the time it takes to the sound wave to travel from the person and then go back

Isolating $d$ :

$d=V.t$ (4)

$d=(343.60 m/s)(2.5 s)$ (5)

Finally:

$d=850 m$

7 0

3 years ago

Which is an example of a chemical change?

Mashutka [201]

Answer:

Burning wax

Explanation:

because in burning, wax reacts with oxygen present in the surrounding and forms carbon dioxide and ash

7 0

3 years ago

Read 2 more answers

A meter stick balances horizontally on a knife-edge at the 50.0 cm mark. With two 4.79 g coins stacked over the 28.8 cm mark, th

masha68 [24]

To solve the exercise, the key concept to be addressed is the Mass Center.

The center of mass of an object is measured as,

$X_{cm} = \frac{\sum m_ix_i}{\sum m_i}$

$X_{cm} = \frac{m_1x_1+m_2x_2+m_3x_3}{m_1+m_2+m_3}$

Our values are given by,

$x_1 = 50cm$

$m_1 = ?$

$x_2 =28.8cm$

$m_2 = 4.79g$

$x_3 = 28.8cm$

$m_3 = 4.79g$

$X_{cm} = 38.4cm$

Replacing the values in our previous equation we have,

$X_{cm} = \frac{m_1x_1+m_2x_2+m_3x_3}{m_1+m_2+m_3}$

$38.4 = \frac{m_1(50)+2(28.8*4.79)}{m_1+2*4.79}$

$38.4(m_1+2*4.79)= m_1(50)+2(28.8*4.79)$

$38.4m_1 +367.872 = 50m_1+275.904$

$11.6m_1 = 91.968$

$m_1 = 7.928g$

Therefore the mass of the meter stick is 7.928g

7 0

3 years ago

A 1.0 kg cart moving right at 5.0 m/s on a frictionless track collides with a second cart moving at 2.0m/s. The 1.0 kg cart has

____ [38]

Answer:

m₂ = 3kg

Explanation:

The question wasn't clear about what direction the initial velocity of the second cart was, so I'll assume it was going left at 2.0m/s.

Anyway, this is a conservation of momentum problem. The equation you need to use is the one written in blue. They want you to solve for the mass of the second cart, so do some algebra and rearrange that blue equation in term of m₂.

Now that you have the equation for m₂, plug in all the values given from the question and you'll get 3kg.

3 0

4 years ago