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lara31 [8.8K]
3 years ago
6

An electric motor consumes 8.40 kJ of electrical energy in 1.00 min. Part A If one-third of this energy goes into heat and other

forms of internal energy of the motor, with the rest going to the motor output, how much torque will this engine develop if you run it at 2900 rpmrpm
Physics
1 answer:
Salsk061 [2.6K]3 years ago
3 0

Answer:

The torque is 0.31 Nm.

Explanation:

Electrical energy, E = 8400 J

time, t = 1 min

Angular speed, w = 2900 rpm = 303.53 rad/s

efficiency = 2/3 of input power

The toque is given by  

P =\tau  w\\\\\frac{2}{3}\times \frac{E}{t}=\tau w\\\\\frac{2}{3}\times \frac{8400}{60}=\tau \times 303.53\\\\\tau =0.31 Nm

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Water has a high specific heat capacity. Oil has a smaller heat capacity.
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An elevator together with its passengers weights 5000 N. At a certain instant, the tension in its supporting cable is 6000 N. De
gayaneshka [121]
We have to forces acting on the system (elevator+passengers):
1) The weight (W=5000 N), acting downward
2) The cable's tension (T=6000 N), acting upward
So, the two forces have opposite direction. The resultant (in upward direction) will be
F=T-W
And for Newton's second law, the resultant of the forces acting on the system causes an acceleration on the system itself, given by
a= \frac{F}{m}
where m is the mass of the system.

So, we need to find F and m.
The resultant of the forces is
F=T-W=6000 N-5000 N=1000 N
To find m, we can use the weight of the system. In fact, the weight of an object is given by
W=mg
where g=9.81 m/s^2. Solving for m, and using W=5000 N, we find
m= \frac{W}{g}= \frac{5000 N}{9.81 m/s^2}=510 kg

and at this point, we can calculate the acceleration of the system (elevator+people):
a= \frac{F}{m}= \frac{1000 N}{510 kg}=1.96 m/s^2
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8 0
3 years ago
A wire with a length of 150 m and a radius of 0.15 mm carries a current with a uniform current density of 2.8 x 10^7A/m^2. The c
Mrac [35]

Answer:

The current is 2.0 A.

(A) is correct option.

Explanation:

Given that,

Length = 150 m

Radius = 0.15 mm

Current densityJ=2.8\times10^{7}\ A/m^2

We need to calculate the current

Using formula of current density

J = \dfrac{I}{A}

I=J\timesA

Where, J = current density

A = area

I = current

Put the value into the formula

I=2.8\times10^{7}\times\pi\times(0.15\times10^{-3})^2

I=1.97=2.0\ A

Hence, The current is 2.0 A.

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3 years ago
1pt If the room is the frame of reference for the study of an object moving in three dimensions, from where should distances be
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Answer:

Option B, two walls and the floor

Explanation:

The distance should be measured from the point where at least the three axed meet.

Two walls and the floor are equivalent to three axes.

Vertical wall 1 = Y Axis

Horizontal wall2 = X Axis

Floor = Z Axis

Thus, the distance should be measured from the point where two walls and one floor meet.

Option , B is correct

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3 years ago
If the wavelength of an s-wave is 23,000 m, and its speed 4500 m/s, what is its frequency?
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Answer:

5 metre.

Explanation:

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= 23,000/ 4,500

= 5 metre.

3 0
3 years ago
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