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2 years ago

Which of the following is one way that an electric motor's rotation speed can be controlled?

Physics

2 answers:

denis23 [38]2 years ago

6 0

The answer is by varying the amount of current flowing to the motor

malfutka [58]2 years ago

5 0

Depending on which type of motor you're talking about, but the first 3 are true. A stronger magnetic field in a DC motor will slow it down but increase its torque.
The amount of current in the motor will control the magnetic fields and therefore affect the speed (and torque). In an induction motor, the rotational speed is given by $n= \frac{120f}{p}$ where f is the line frequency and p is the number of poles. Thus fewer poles makes it go faster.

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A car accelerates from rest at 2 m/s. what is the speed after 8 sec?

beks73 [17]

Answer:

16m/s

Explanation:

$v_{f}=v_{i}+at$

$v_{f}=0+2\cdot8$

$v_{f}=16\ \frac{m}{s}$

Therefore, the speed after 8 seconds is 16m/s

6 0

2 years ago

Because of surface tension, it is possible, with care, to support an object heavier than water on the water surface. The maximum

boyakko [2]

Answer:

$\pi 1 = \frac{h}{l}$

$\pi 2 =$ б / $l^2gp$

$\frac{h}{l} =$ Ф ( б / $l^2gp$ )

Explanation:

<u>Develop a suitable set of dimensionless parameters for this problem</u>

The set of dimensionless parameters for this problem is :

$\pi 1 = \frac{h}{l}$

$\pi 2 =$ б / $l^2gp$

$\frac{h}{l} =$ Ф ( б / $l^2gp$ )

and they are using the pi theorem, MLT systems

attached below is a detailed solution

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2 years ago

Why is it impossible to create a perpetual motion machine?

enyata [817]

Answer:

The first law of thermodynamics is the law of conservation of energy. It states that energy is always conserved. ... To keep a machine moving, the energy applied should stay with the machine without any losses. Because of this fact alone, it is impossible to build perpetual motion machines.

Explanation:

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2 years ago

How does drag affect the cost of owning a car?

vodka [1.7K]

Answer:

You’ve probably noticed over the years that car design has become more streamlined. In other words, most consumer vehicles don’t look very boxy anymore. Some of this is due to aesthetics, but much of it is meant to decrease a vehicle’s drag coefficient. A cube has a high drag coefficient, whereas a teardrop has a low one.

By decreasing the drag coefficient, car makers are helping vehicles “slip” through air more easily. That reduces the amount of fuel needed to move the vehicle, and the difference shows up in your wallet and in the environment.

Explanation:

~Ban~

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2 years ago

Read 2 more answers

What is the magnitude of the velocity of a 25 kg mass that is moving with a momentum of 100 kg*m/s?

Gekata [30.6K]

Answer:

v= 4 m/s

Explanation:

Momenutm is, by definition, the product of mass and velocity.

$p = mv$