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3 years ago

An object has a kinetic energy Ek. What happens to the kinetic energy if we:

1 answer:

3 0

The energy possessed by a body because of its motion, equal to one half the mass of the body times the square of its speed is called its kinetic energy.
K=
2
1

mv
2

When, v=2v,
K
′
=
2
1

m(2v)
2

K
′
=4×
2
1

mv
2

K
′
=4K
Hence, when velocity is doubled, kinetic energy becomes 4 times.

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podryga [215]

Answer:

yeah righto the correct answer mate would be D) :)

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3 years ago

A brass cube, 10 cm on a side, is raised in temperature

lana [24]

Answer:

$\delta L\%=22.5\%$

Explanation:

Assuming that the thermal expansion of brass cube occurs isotropically (i.e. equal in all the directions).

Given:

length of the cube, $l=10\ cm=0.1\ m$

change in temperature of the cube, $\Deta T=200\^{\circ}C$

coefficient of volume expansion, $\beta=57\times 10^{-6}\ ^{\circ}C^{-1}$

Hence volume of the cube:

$V=10^{-3}\ m^3$

Now the volume of the cube after expansion:

$\delta V=V.\beta.\Delta T$

$\delta V=10^{-3}\times 57\times 10^{-6}\times 200$

$\delta V=1.14\times 10^{-5}\ m^3$

Therefore,

$\delta L=0.0225\ m$

Now the percentage change in the edges of the cube:

$\delta L\%=\frac{\delta L}{L} \times 100$

$\delta L\%=\frac{0.0225}{0.1} \times 100$

$\delta L\%=22.5\%$

5 0

3 years ago

The angular momentum of a flywheel having a rotational inertia of 0.200 kg · m2 about its central axis decreases from 3.80 to 0.

Bingel [31]

Answer:

14.3065 rad

-36.777 J

-28.29 W

Explanation:

$L_f$ = Final angular momentum = 0.6 kgm²/s

$L_i$ = Initial angular momentum = 3 kgm²/s

I = Moment of inertia = 0.2 kgm²

Torque is given by

$\tau=\dfrac{L_f-L_i}{t}\\\Rightarrow \tau=\frac{0.6-3.8}{1.3}\\\Rightarrow \tau=-2.46\ Nm$

$\theta=\omega_it+\dfrac{1}{2}\alpha t^2$

Initial angular speed is given by

$\omega_i=\dfrac{L_i}{I}$

Angular acceleration is given by

$\alpha=\dfrac{\tau}{I}$

$\theta=\omega_it+\dfrac{1}{2}\alpha t^2\\\Rightarrow \theta=\dfrac{L_it+\dfrac{1}{2}\tau t^2}{I}\\\Rightarrow \theta=\dfrac{3.8\times 1.3+\dfrac{1}{2}\times -2.46\times 1.3^2}{0.2}\\\Rightarrow \theta=14.3065\ rad$

The angle is 14.3065 rad

Work done is given by

$W=\tau \theta\\\Rightarrow W=-2.46\times 14.95\\\Rightarrow W=-36.777\ J$

The work done on the wheel is -36.777 J

Power is given by

$P=\dfrac{W}{t}\\\Rightarrow P=\dfrac{-36.777}{1.3}\\\Rightarrow P=-28.29\ W$

The power is -28.29 W

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3 years ago

Suppose you are a particle of water in a lake. Describe what happens to you when a motorboat passes by. Be sure to use words lik

snow_lady [41]

The boat could easily pass through me ( particle of water) because the forces of attraction between the particles and the density is less than the particles of a solid.

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4 years ago

What health benefits can you get from consuming fiber? (Select all that apply.)

velikii [3]

Answer:

I know it is the first one but I think it is the third one too but you would have to double check me

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3 years ago

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