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3 years ago

14

An object accelerates to a velocity of 230 m/s over a time of 2.5 s. The acceleration it experienced was 42 m/s2. What was its i

nitial velocity?

1 answer:

zmey [24]3 years ago

5 0

Answer:

230 = x + 105

x= 125

Explanation:

v = v0 + at

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Which of the following is a method used to prevent soil erosion?

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I believe the answer is B. <span>Contour farming
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4 years ago

A 50.0 kg child stands at the rim of a merry-go-round of radius 1.95 m, rotating with an angular speed of 2.80 rad/s.

eimsori [14]

Answer:

a) ac= 15.3 m/s² b) 765 N c) 1.56

Explanation:

a) For the child standing in the rim of the merry-go-round, there exists a force, called centripetal force, that keeps her moving in a circular path, and not going in a straight line at constant speed, as Newton's first law dictates.

The acceleration cosequence of this force is called centripetal acceleration, and it can be showed be equal to the following expression:

ac = ω²*r, where ω is the angular speed, and r is the radius.

Replacing by the givens:

ac= (2.8)² (rad/sec)² * 1.95 m = 15.3 m/s²

b) As we were talking about the centripetal force, we realize that this can't be some type of an unknown force, so, it must be one than can be identifiable.

Looking at the external forces on the child, the only one that is applied in horizontal plane, is the friction force.

So, this friction force, is just the centripetal force we were talking about.

The mimimum force between her feet and the floor of the carousel, is just the centripetal force:

Fc = m*ac = 50.0 kg * 15.3 m/s² = 765 N

c) The friction force can take any value, in order to be equal to the centripetal force, up to a limit value, beyond which , the child will move. This limit value can be expressed as follows:

Fs max = μs*N = μs*m*g

⇒ m*ac = μs*m*g

Simplifying common terms, we can solve for the coefficient of static friction , μs, as follows:

μs = 15. 3 m/s² / 9.8 m/s² = 1.56

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4 years ago

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3 years ago

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3 years ago

Which of electromagnetic radiation has the shortest wavelength?

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Answer:

The electromagnetic radiation with the shortest wavelength are gamma rays.

Explanation:

Photons are the particles that constitute light and its kwnow that lights propagates as electromagnetic waves.

The electromagnetic spectrum is the distribution of radiation due to the different frequencies at which it radiates and its different intensities, that radiation is formed by electromagnetic waves, which are transverse waves formed by an electric field and a magnetic field perpendicular to it.

The distribution of the radiation in the electromagnetic spectrum can also be given in wavelengths, but it is more frequent to work with it at frequencies, the highest being that of gamma rays, followed by X-rays, ultraviolet rays and the visible region , and those of lower frequencies, which correspond to infrared, microwave and radio waves.

The energy given for each wavelength can be found by means of the following equation.

$E = h\nu$ (1)

but $c = \lambda \cdot \nu$

$\nu = \frac{c}{\lambda}$

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Where E is the energy, h is the planck's constant and $\lambda$ is the wavelength.

So, it can be see in equation 2 that when the wavelength increases the energy decreases (inversely proportional).

Hence, the electromagnetic radiation with the shortest wavelength are gamma rays.

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3 years ago