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elena55 [62]
3 years ago
12

The armature windings of a dc motor have a resistance of 5.0 Ω. The motor is connected to a 120-V line, and when the motor reach

es full speed against its normal load, the back emf is 108 V. The load is increased so it causes the motor to run at half speed.
What will be the current in the motor in this case?
Physics
1 answer:
Snezhnost [94]3 years ago
3 0

Answer:

The current in the motor in this case is 13.2 A

Explanation:

Given:

Resistance R = 5 Ω

Emf E = 120 V

Induced emf E _{induced} = 108 V

When motor run at half speed due to load increased then induced emf is also reduced to half of its value

So new induced emf in our case is given by,

E_{induced }  = \frac{108}{2} = 54 V

  I = \frac{V}{R}

Where V = E - E_{Induced }

  I = \frac{120-54}{5}

  I = 13.2 A

Therefore, the current in the motor in this case is 13.2 A

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7 0
3 years ago
A student of mass 60.0 kg, starting at rest, slides down a slide 20.0 m long, tilted at an angle of 30.0° with respect to the ho
cricket20 [7]

Answer:

Explanation:

Reaction force of inclined surface

R = mgcos30

=60 x 9.8 x .866

= 509 N

Force of kinetic friction

= .12 x 509

= 61.08 N

b )

net force downwards = mgsinθ - μmgcosθ

acceleration = g sinθ - μgcosθ

9.8 sin30 - .12 x 9.8 x cos30

= 4.9 - 1.018

a= 3.88 m /s²

c )

v² = 2as

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A fiber-optic cable (n = 1.53) is submerged in water (n = 1.33). Predict whether light will be refracted or whether it will unde
Aleks [24]
Total internal refraction occurs when a ray of light meets the following conditions. 
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2. The angle of incident in the denser media must be greater than the critical angle. 

In the case above the fiber-optic is optically denser than water. Since the light is incident to fiber-optic-water interface, then one condition is fulfilled.
Checking the other condition we carry out the calculation below;

n1sinФ1=n2sinФ2
where c ⇒critical angle  
1.53 sinc = 1.33 sin 90
sinc =0.86928
   c = 60.37° 

The angle of incident is (65°-70°) is greater than critical angle. 
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Cellular respiration in the body cells require oxygen to produce energy which are used by the muscles and other body cells. Carbon dioxide is also produced and is the build up of carbon dioxide has to be removed from the body as the by product of cellular respiration which is toxic at the cell level

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