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Helga [31]
1 year ago
12

A sled having a certain initial speed on a horizontal surface comes to rest after traveling 10 m. If the coefficient of kinetic

friction between the object and the surface is 0.20, what was the initial speed of the object
Physics
1 answer:
sergiy2304 [10]1 year ago
5 0

Answer:

the initial speed of the object is 6.26 m/s

Explanation:

given information:

distance, s = 10 m

the coefficient of kinetic friction, μ = 0.2

we use the equation where the kinetic energy is equal to the friction force.

kinetic energy, KE = \frac{1}{2} mv^{2}

friction work,  W = F(friction) s

KE = W

\frac{1}{2} mv^{2} = F(friction) s

where, F(friction) = μ N, N is normal force (N = m g)

                            = μ m g

so,

\frac{1}{2} mv^{2} = μ m g s

\frac{1}{2} v^{2} = μ g s

v^{2} = 2 μ g s

  = 2 (0.2) (9.8) (10)

  = 39.2

hence,

v = \sqrt{3.92}

  = 6.26 m/s

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Two large parallel conducting plates carrying opposite charges of equal magnitude are separated by 2.20 cm. Part A If the surfac
alukav5142 [94]

Answer:

5308.34 N/C

Explanation:

Given:

Surface density of each plate (σ) = 47.0 nC/m² = 47\times 10^{-9}\ C/m^2

Separation between the plates (d) = 2.20 cm

We know, from Gauss law for a thin sheet of plate that, the electric field at a point near the sheet of surface density 'σ' is given as:

E=\dfrac{\sigma}{2\epsilon_0}

Now, as the plates are oppositely charged, so the electric field in the region between the plates will be in same direction and thus their magnitudes gets added up. Therefore,

E_{between}=E+E=2E=\frac{2\sigma}{2\epsilon_0}=\frac{\sigma}{\epsilon_0}

Now, plug in  47\times 10^{-9}\ C/m^2 for 'σ' and 8.85\times 10^{-12}\ F/m for \epsilon_0 and solve for the electric field. This gives,

E_{between}=\frac{47\times 10^{-9}\ C/m^2}{8.854\times 10^{-12}\ F/m}\\\\E_{between}= 5308.34\ N/C

Therefore, the electric field between the plates has a magnitude of 5308.34 N/C

5 0
1 year ago
According to the article, which pattern of brain waves are most conducive to studying new information?
sashaice [31]
Alpha brain waves are those most conducive to studying new information.

When consciously alert, we generally function along a beta brain rhythm. In diminishing this rhythm to alpha, we transition into a state of physical and mental relaxation that is ideal for learning new information and storing facts and  data. Studies have shown that the effect of decreasing brain rhythm is linked to feelings of increased mental clarity and remembrance. As it is a prime condition for synthetic thought and creativity, it becomes easier to visualize and create associations (information is better learned and absorbed by using such study methods). 

Hope this helps! :)
7 0
1 year ago
An astronomer observes that the wavelength of light from a distant star is shifted toward the red part of the visible spectrum.
balandron [24]

Answer:

The distance between the earth and the star is increasing.

Explanation:

When we observe an object and its electromagnetic radiation has been displaced to blue, it means that it is getting closer to us, causing the light waves it emits to get closer together and its wavelength to decrease towards blue, this is knowm as blueshift.

On the contrary, when an object is rapidly moving away from us, the light waves or electromagnetic radiation it emits have been stretched from their normal wavelength to a longer wavelength, towards the red part of the spectrum. This is known as redshift.

This phenomenon of changes in wavelength and frequency due to movement (whether the source approaches or moves away) is described by the Doppler effect.

So for this case because the light we perceive from the star has moved to the red part of the visible spectrum, we can conclude that it is moving away from the earth, and that the distance between the star and the earth is increasing.

7 0
2 years ago
You have a suspect on the run in a dry, wooded area; they’ve ditched the gun but are hiding from you. how long do you have to fi
erma4kov [3.2K]

Answer:

C. a few days

Explanation:

The evidence that we will have to investigate is the gunshot residue on the body of the suspect. When a person fires a gun there will be a deposition of material from the components of the chemicals present in the gun. This deposit is called gunshot residue and consists of particles of the propellant or explosive primer.

Experimentation has shown that the period of time that is person will test possible for gunshot residue is 5.27 days.

7 0
1 year ago
A nucleus whose mass is 3.499612×10^(−25) kg undergoes spontaneous alpha decay. The original nucleus disappears and there appear
Elanso [62]

Answer:

The sum of the kinetic energies of the alpha particle and the new nucleus = (6.5898 × 10⁻¹³) J

Explanation:

Old nucleus ---> New nucleus + alpha particle.

We will use the conservation of energy theorem for extremely small particles,

Total energy before split = total energy after split

That is,

Total energy of the original nucleus = (total energy of the new nucleus) + (total energy of the alpha particle)

Total energy of these subatomic particles is given as equal to (rest energy) + (kinetic energy)

Rest energy = mc² (Einstein)

Let Kinetic energy be k

Kinetic energy of original nucleus = k₀ = 0 J

Kinetic energy of new nucleus = kₙ

Kinetic energy of alpha particle = kₐ

Mass of original nucleus = m₀ = (3.499612 × 10⁻²⁵) kg

Mass of new nucleus = mₙ = (3.433132 × 10⁻²⁵) kg

Mass of alpha particle = mₐ = (6.640678 × 10⁻²⁷) kg

Speed of light = c = (3.0 × 10⁸) m/s

Total energy of the original nucleus = m₀c² (kinetic energy = 0, since it was originally at rest)

Total energy of new nucleus = (mₙc²) + kₙ

Total energy of the alpha particle = (mₐc²) + kₐ

(m₀c²) = (mₙc²) + kₙ + (mₐc²) + kₐ

kₙ + kₐ = (m₀c²) - [(mₙc²) + (mₐc²)

(kₙ + kₐ) = c² (m₀ - mₙ - mₐ)

(kₙ + kₐ) = (3.0 × 10⁸)² [(3.499612 × 10⁻²⁵) - (3.433132 × 10⁻²⁵) - (6.640678 × 10⁻²⁷)]

(kₙ + kₐ) = (9.0 × 10¹⁶)(0.00007322 × 10⁻²⁵) = (6.5898 × 10⁻¹³) J

5 0
1 year ago
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