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3 years ago

Times will the kinetic one

Physics

1 answer:

mixer [17]3 years ago

3 0

Answer:

The new kinetic energy is 9 times of the initial kinetic energy.

Explanation:

The kinetic energy of an object is given by the formula as follows :

$E=\dfrac{1}{2}mv^2$

Where

m is mass and v is speed of the body

If the speed of the body is tripled. Let v' is the new speed, v' = 3v. The new kinetic energy is E' and it is given by :

$E'=\dfrac{1}{2}mv'^2\\\\\text{Put v' = 3v}\\\\E'=\dfrac{1}{2}m\times (3v)^2\\\\=\dfrac{1}{2}m\times 9v^2\\\\=9\times (\dfrac{1}{2}mv^2)\\\\E'=9\times E$

Hence, the new kinetic energy is 9 times of the initial kinetic energy.

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A boy is pulling a box on the ground by a string to the right. What four forces he using?

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Un cuerpo de 480 g de masa es atraído con una fuerza de 3.9 E-6 N por otro cuerpo de 196 g de masa. Calcula la distancia a la qu

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Answer:

La distancia entre los dos cuerpos es aproximadamente 1.269 milímetros.

Explanation:

Asumamos que ambos cuerpos son partículas, la fuerza de atracción ( $F$ ), en newtons, entre ambos cuerpos se define mediante la Ley de Newton de la Gravitación Universal, cuya ecuación es:

$F = G \cdot \frac{m_{1}\cdot m_{2}}{r^{2}}$ (1)

Donde:

$G$ - Constante de la gravitación universal, en metros cúbicos por kilogramo-segundo cuadrado.

$m_{1}, m_{2}$ - Masas de los cuerpos, en kilogramos.

$r$ - Distancia entre los cuerpos, en metros.

Si sabemos que $G = 6.674\times 10^{-11}\,\frac{m^{3}}{kg\cdot s^{2}}$ , $m_{1} = 0.48\,kg$ , $m_{2} = 0.196\,kg$ y $F = 3.9\times 10^{-6}\,N$ , entonces la distancia entre los dos cuerpos es:

$r = \sqrt{\frac{G\cdot m_{1}\cdot m_{2}}{F} }$

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3 years ago

Older railroad tracks in the U.S. are made of 12-m-long pieces of steel. When the tracks are laid, gaps are left between section

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Answer: ∆L = 0.49cm ≈ 0.50cm

Therefore there should be 0.5 cm gap between each piece of steel.

Explanation:

Thermal expansion of steel is the increase in size of steel as a result of increased temperature. It can be represented by the mathematical expression:

∆L = L(k)∆T .....1

Where;

∆L is the change in length

L is the initial length

∆T is the change in temperature

k is the specific Linear expansion coefficient.

Given;

L = 12m

∆T = 50°C - 16°C = 34°C

k (for steel) = 1.2 × 10^-6 /C

Substituting the values into the equation 1

∆L = 12 × 34 × 12×10^-6

∆L = 4896 × 10^-6 m

∆L = 0.49cm ≈ 0.50cm

Therefore there should be 0.5 cm gap between each piece of steel.

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3 years ago

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The engine that moves the cables for the San Francisco cable cars delivers 390.3 kW of power for each line. How long does it tak

Musya8 [376]

Answer:

It would take 16.7 s for the work to be done by the engine.

Explanation:

From the question, given: Power = 390.3 kW

Work to be done = 6.5 x $10^{6}$ J

But, power and work done with respect to time, has a relationship of:

Power = $\frac{work done}{time}$

So that,

time = $\frac{work done}{Power}$

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= 16.6539

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Time required is 16.7 seconds.

Thus, it would take 16.7 s for the work to be done by the engine.

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3 years ago