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3 years ago

Burning can be:

Physics

2 answers:

Rufina [12.5K]3 years ago

8 0

Answer:

Controlled for useful work

Explanation:

kolezko [41]3 years ago

3 0

Controlled for useful work

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The flywheel of a steam engine runs with a constant angular velocity of 190 rev/min. When steam is shut off, the friction of the

Ivanshal [37]

Answer:

(a) $\alpha = - 1.32\ rev/m^{2}$

(b) $\theta = 13674\ rev$

(d) $a = 22.458\ m/s^{2}$

Solution:

As per the question:

Angular velocity, $\omega = 190\ rev/min$

Time taken by the wheel to stop, t = 2.4 h = $2.4\times 60 = 144\ min$

Distance from the axis, R = 38 cm = 0.38 m

Now,

(a) To calculate the constant angular velocity, suing Kinematic eqn for rotational motion:

$\omega' = \omega + \alpha t$

$omega'$ = final angular velocity

$\omega$ = initial angular velocity

$\alpha$ = angular acceleration

Now,

$0 = 190 + \alpha \times 144$

$\alpha = - 1.32\ rev/m^{2}$

Now,

(b) The no. of revolutions is given by:

$\omega'^{2} = \omega^{2} + 2\alpha \theta$

$0 = 190^{2} + 2\times (- 1.32) \theta$

$\theta = 13674\ rev$

(c) Tangential component does not depend on instantaneous angular velocity but depends on radius and angular acceleration:

$\alpha_{tan} = 0.38\times 1.32\times \frac{2\pi}{3600} = 8.75\times 10^{- 4}\ m/s^{2}$

(d) The radial acceleration is given by:

$\alpha_{R} = R\omega^{2} = 0.32(80\times \frac{2\pi}{60})^{2} = 22.45\ rad/s$

Linear acceleration is given by:

$a = \sqrt{\alpha_{R}^{2} + \alpha_{tan}^{2}}$

$a = \sqrt{22.45^{2} + (8.75\times 10^{- 4})^{2}} = 22.458\ m/s^{2}$

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3 years ago

Two pulleys, one with a radius 2R and one with a radius of R, are welded together and can rotate about the same axis. A block is

Arisa [49]

Answer:

speed will double

Explanation:

Tangential velocity is given by

v=wr

where r is radius and w is rotational velocity. When r is increased to 2R, keeping roational velocity constant, the tangential velocity doubles. Hence unwinding will take place at a twice the rate and the final velocity will be double

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Which of the following describes the genotypes and the phenotype of parents whose child will definitely have a recessive trait

VikaD [51]

The answer is letter A

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3 years ago

How does light reflect off of mirrors and other types of surfaces?

Marat540 [252]

Light can reflect from mirrors because mirrors are a prism.

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3 years ago

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A 4.2-m-diameter merry-go-round is rotating freely with an angularvelocity of 0.80 rad/s. Its total moment of inertia is1760kgm2

ASHA 777 [7]

Answer

given,

mass of people = 65 kg

number of people =

diameter of the merry-go-round = 4.2 m

radius = 2.1 m

angular velocity = 0.8 rad/s

moment of inertia = 1760 kg m²

Using the law of conservation of angular momentum, we have

L₁= L₂

I₁ω₁ =I₂ω₂

I₁ω₁= ( I₁+ 4 m r²)ω²

( 1760 x 0.8) = ( 1760 + 4 x 65 x 2.12)ω²

1408 = 2311.2 ω²

ω² = 0.609

ω = 0.781 rad/s

b) If the people jump of the merry-go-round radially, they exert no torque.

hence, it will not change the angular momentum of the merry-go-round. It will continue to move with the same ω .

7 0

4 years ago