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Leviafan [203]
3 years ago
12

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

Physics
2 answers:
denis23 [38]3 years ago
6 0

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


malfutka [58]3 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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Jen pushed a box for a distance of 80m with 20 N of force. How much work did she do?
Drupady [299]
The answer is 1,600 J.

A work (W) can be expressed as a product of a force (F) and a distance (d):
W = F · d<span>

We have:
W = ?
F = 20 N = 20 kg*m/s</span>²
d = 80 m
_____
W = 20 kg*m/s² * 80 m
W = 20 * 80 kg*m/s² * m
W = 1600 kg*m²/s²
W = 1600 J
8 0
3 years ago
The 1.0-kg collar slides freely on the fixed circular rod. Calculate the velocity v of the collar as it hits the stop at B if it
soldi70 [24.7K]

Answer:

6.21 m/s

Explanation:

Using work energy equation then

U_{1-2}=T_B- T_A\\58d-mgh=0.5m(v_b^{2}-v_a^{2})

where d is displacement from initial to final position, v is velocity and subscripts a and b are position A and B respectively, m is mass of collar, g is acceleration due to gravity

Substituting 1 Kg for m, 0.4m for h, v_a as 0, 9.81 for g then

58(\sqrt{0.4^{2}+0.3^{2}}-0.1)-(1\times 9.81\times 0.4)=0.5\times 1\times (v_b^{2}-v_a^{2})\\19.276=0.5\times 1v_b^{2}\\v_b=6.209025688 m/s\approx 6.21 m/s

7 0
3 years ago
Suppose you run into a wall at 4.5 meters per second (about 10 mph). Let's say the wall brings you to a complete stop in 0.5 sec
STatiana [176]

Answer with Explanation:

We are given that

Initial velocity,u=4.5 m/s

Time=t =0.5 s

Final velocity=v=0m/s

We have to find the deceleration and estimate the force exerted by wall on you.

We know that

Acceleration=\frac{v-u}{t}

Using the formula

Acceleration=a=\frac{0-4.5}{0.5}

deceleration=a=-9m/s^2

We know that

Force =ma

Using the formula and suppose mass  of my body=m=40 kg

The force exerted by wall on you

Force=40\times (9)=360N

3 0
3 years ago
For main sequence stars what tends to happen to the absolute brightness of a star as the temperature rises? How do you know?
professor190 [17]

With the increase in the temperature of the star, the brightness of the stars will also increase.

<u>Explanation:</u>

The brightness and surface temperature of stars ordinarily increment with age. A star stays close to its underlying situation on the fundamental arrangement until a lot of hydrogen in the center has been devoured, at that point starts to advance into a progressively brilliant star.

The brightness of a star relies upon its structure and how far it is from the planet. Space experts characterize star brilliance as far as clear extent — how splendid the star shows up from Earth — and outright greatness — how brilliant the star shows up at a standard separation

6 0
3 years ago
Help me please!!!!!!!!!
beks73 [17]

limiting frictionl force

6 0
3 years ago
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