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anyanavicka [17]
2 years ago
9

A train travels 4200 km in 90 hours. What is its speed?

Physics
1 answer:
denis23 [38]2 years ago
6 0

Answer: I think its 120

Explanation: thx for the free points :)

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zavuch27 [327]

Answer:

The SI unit of power is the watt

Explanation:

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3 years ago
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You stand on a frictional platform that is rotating at 1.1 rev/s. Your arms are outstretched, and you hold a heavy weight in eac
bezimeni [28]

Answer:

a) The resulting angular speed of platform is 1.38 rev/sec

b) The change in kinetic energy of the system is 53 J.

Explanation:

This question is incomplete. The complete question will be:

You stand on a frictional platform that is rotating at 1.1 rev/s. Your arms are outstretched, and you hold a heavy weight in each hand. The moment of inertia of you, the extended weights, and the platform is 8.8 kg · m2. When you pull the weights in toward your body, the moment of inertia decreases to  7.0 k g .m 2  

a) What is the resulting angular speed of the platform? Answer in units of r e v / s .

b)What is the change in kinetic energy of the system? Answer in units of J.

<h3>ANSWER:</h3>

a)

we know that:

Angular Momentum = L = Iω

From conservation of momentum:

Lo = Lf

(Io) (ωo) = (If) (ωf)

ωf = (Io) (ωo)/(If)

ωf = (8.8 kg.m²)(1.1 rev/s)/(7.0 kg.m²)

<u>ωf = 1.38 rev/sec =</u>

b)

ωf = (1.38 rev/sec)(2π rad/ 1 rev) = 8.67 rad/sec

ωo = (1.1 rev/sec)(2π rad/ 1 rev) = 6.91 rad/sec

The kinetic energy for rotational motion is given as:

K.E = (1/2)Iω²

Thus, the change in kinetic energy will be:

ΔK.E = (K.E)f - (K.E)o

ΔK.E = (1/2)Ifωf² - (1/2)Ioωo²

ΔK.E = (1/2)(Ifωf² - Ioωo²)

ΔK.E = (1/2)[(7 kg.m²)(8.67 rad/sec)² - (8.8 kg.m²)(6.91 rad/sec)²

<u>ΔK.E = 53 J</u>

5 0
2 years ago
Plssss help I need good grade!!!! Plssss and thank u
shepuryov [24]

Answer:

the answer is 'b'

According to me

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It would be the <span>Energy Therapies Reiki that is a common type of work wherein it makes use of touch and visualisation. In addition, this kind of therapy has its primary goal just to lessen stress and furthermore promotes relaxation. The technique is said to be making use of a "life force energy."</span>
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3 years ago
Someone please help !!
masha68 [24]
I’m pretty sure it’s c.... hope it helps and hope it’s right.
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