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3 years ago

You accidentally drop a book down a stairwell. Assuming no air resistance, How fast will the book be moving after 1.1 second?

Physics

2 answers:

vazorg [7]3 years ago

7 0

Answer: 10.8 m/s

Explanation: Rounding up

nlexa [21]3 years ago

3 0

It would be accelerating at -9.8 m/s^2 so it’s velocity would be equal to -9.8•1.1 so the answer is 10.78m/s

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A cylinder with rotational inertia I1 = 2.0 kg·m2 rotates clockwise about a vertical axis through its center with angular speed

bazaltina [42]

Answer:

a) The angular speed of the combination is 0.667 radians per second (clockwise).

b) 98.829 per cent is lost due to friction.

Explanation:

a) Since no external load applied on any of the cylinders before, during and after the coupling, angular momentum of the entire system is constant. In consequence, we apply the Principle of Angular Momentum Conservation to calculate the final angular speed of the combination:

$I_{1}\cdot \omega_{1} + I_{2}\cdot \omega_{2} = (I_{1}+I_{2})\cdot \omega$ (1)

Where:

$I_{1}$ - Moment of inertia of the first cylinder, in kilogram-square meters.

$I_{2}$ - Moment of inertia of the second cylinder, in kilogram-square meters.

$\omega_{1}$ , $\omega_{2}$ - Initial angular speeds of the first and second cylinder, in radians per second.

$\omega$ - Final angular speed of the entire system, in radians per second.

If we know that $I_{1} = 2\,kg\cdot m^{2}$ , $I_{2} = 1\,kg\cdot m^{2}$ , $\omega_{1} = -5\,\frac{rad}{s}$ and $\omega_{2} = 8\,\frac{rad}{s}$ , then the final angular speed of the entire system is:

$\omega = \frac{I_{1}\cdot \omega_{1}+I_{2}\cdot \omega_{2}}{I_{1}+I_{2}}$

$\omega = -0.667\,\frac{rad}{s}$

The angular speed of the combination is 0.667 radians per second (clockwise).

b) By Principle of Energy Conservation and Work-Energy Theorem, the energy lost due to friction ( $E_{loss}$ ), in joules, is equal to the change in the total kinetic energy of the system. Given that both cylinder have pure rotation, kinetic energy is due to only rotation. That is:

$E_{loss} = \frac{1}{2} \cdot (I_{1}\cdot \omega_{1}^{2}+I_{2}\cdot \omega_{2}^{2}) - \frac{1}{2}\cdot (I_{1}+I_{2})\cdot \omega^{2}$ (2)

If we know that $I_{1} = 2\,kg\cdot m^{2}$ , $I_{2} = 1\,kg\cdot m^{2}$ , $\omega_{1} = -5\,\frac{rad}{s}$ , $\omega_{2} = 8\,\frac{rad}{s}$ and $\omega = -0.667\,\frac{rad}{s}$ , then the energy lost due to friction is:

$E_{loss} = \frac{1}{2} \cdot (I_{1}\cdot \omega_{1}^{2}+I_{2}\cdot \omega_{2}^{2}) - \frac{1}{2}\cdot (I_{1}+I_{2})\cdot \omega^{2}$

$E_{loss} = 56.333\,J$

The original amount of kinetic energy ( $K$ ), in joules, is:

$K = \frac{1}{2} \cdot (I_{1}\cdot \omega_{1}^{2}+I_{2}\cdot \omega_{2}^{2})$

$K = 57\,J$

Lastly, the percentage of the original kinetic energy lost to friction is:

$\%e = \frac{E_{loss}}{K}\times 100\,\%$

$\% e = 98.829\,\%$

98.829 per cent is lost due to friction.

6 0

3 years ago

Which metal and nonmetal families are the most different and why

nevsk [136]

Answer:

since they have got specific and special metallic and non metallic characteristics I guess

3 0

3 years ago

How can being scientifically literate help you in your own life?

stiv31 [10]

Answer: You can betterly understand what's around you and how it works

8 0

2 years ago

An inverted image of an object is viewed on a screen from the side facing a converging lens. An opaque card is then introduced c

Marta_Voda [28]

Answer:

d) The image would be dimmer

Explanation:

When inverted image of an object is viewed on a screen from the side facing a converging lens, the

lens focuses the diverging, and blurred light rays from the distance object through refraction of the rays two times.Then the rays is converge by the double bending cl at a focal point behind the lens inorder for a sharper image to be be observed.

But when an opaque card is then introduced to cover only the upper half of the lens then the image becomes dimmer because of the reduction in the light intensity on the screen by 50%

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3 years ago

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GenaCL600 [577]

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