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3 years ago

What is the difference between low density and high density?

2 answers:

ivann1987 [24]3 years ago

8 0

One of the key differences between high density vs low density can liners is the sound and feeling. High density bags or can liners will have a more stiff feeling and sound "crunchier." In contrast, low density polyethylene bags will be much quieter to the touch and have a softer feel.

i hope this helped! :)

Dafna1 [17]3 years ago

6 0

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A truck going 15 kmôŹ°€h has a head-on collision with a small car going 30 kmôŹ°€h. Which statement best describes the situation

zlopas [31]

1. e) None of the above is necessarily true.

2.d) Without knowing the mass of the boat and the sack, we cannot tell.

5 0

3 years ago

How do you know if an experimental result is acceptable or trustworthy? What gives you confidence that your data are trustworthy

Virty [35]

Explanation:

For an experimental result to be considered acceptable, all relevant variables involved in the experiment must be taken into account, by isolating it, performing it under controlled conditions and modifying the conditions under which it takes place. This, with the objective of excluding alternative explanations in the analisis of the experimental data. Therefore, if these steps are followed appropriately, experimental data are trustworthy. The reliability of the experiment increases when it is replicated by other researchers and the same results are obtained.

6 0

4 years ago

A block of mass M on a horizontal surface is connected to the end of a massless spring of spring constant k. The block is pulled

slamgirl [31]

Answer:

Minimum coefficient of kinetic friction between the surface and the block is $\mu_k=\frac{kx}{2Mg}$ .

Explanation:

Given:

Mass of the block = M

Spring constant = k

Distance pulled = x

According to the question:

We have to find the minimum co-efficient of kinetic friction between the surface and the block that will prevent the block from returning to its equilibrium with non-zero speed.

So,

From the FBD we can say that:

⇒ Normal force, $N=Mg$ ...equation(i)

⇒ Elastic potential energy, $PE$ = $\frac{kx^2}{2}$ ...equation (ii)

⇒ Frictional force, $f$ = $\mu_kN$ ...equation (iii)

⇒ Plugging (i) in (iii).

⇒ $f=\mu_kMg$

Now,

⇒ As we know that the energy lost due to friction is equivalent to PE .

⇒ $PE=fx$ ...considering PE as $mgh$ or $f(x)$ .

Arranging the equation.

⇒ $\frac{kx^2}{2}=\mu_k Mg (x)$

⇒ $\frac{kx}{2}=\mu_k Mg$ ...eliminating x from both sides.

⇒ $\frac{kx}{2Mg}=\mu_k$ ...dividing both sides wit Mg.

Minimum coefficient of kinetic friction between the surface and the block is $\frac{kx}{2Mg}=\mu_k$ .

4 0

4 years ago

a bag of cement is pulled along a horizontal plane by a constant force of 15n calculate the work done in moving the bag through

morpeh [17]

Answer:

300J

Explanation:

Given parameters:

Constant force = 15N

Distance = 20m

Unknown:

Work done = ?

Solution:

Work done is the force applied to move a body through a particular distance.

Work done = Force x distance

So;

Work done = 15 x 20 = 300J

4 0

3 years ago

Atomic hydrogen produces a well-known series of spectral lines in several regions of the electromagnetic spectrum. Each series f

navik [9.2K]

Answer:

n₁ = 3

Explanation:

The energy of the states in the hydrogen atom is explained by the Bohr model, the transitions heal when an electron passes from a state of higher energy to another of lower energy,

ΔE = $E_{nf}$ - E₀ = - k²e² / 2m (1 / $n_{f}$ ²2 - 1 / n₀²)

The energy of this transition is given by the Planck equation

E = h f = h c / λ

h c / λ = -k²e² / 2m (1 / no ²- 1 / no²)

1 / λ = Ry (1/ $n_{f}$ ² - 1 / n₀²)

Let's apply these equations to our case

λ = 821 nm = 821 10⁻⁹ m

E = h c / λ

E = 6.63 10⁻³⁴ 3 10⁸/821 10⁻⁹

E = 2.423 10⁻¹⁹ J

Now we can use the Bohr equation

Let's reduce to eV

E = 2,423 10⁻¹⁹ J (1eV / 1.6 10⁻¹⁹) = 1,514 eV

$E_{nf}$ - E₀ = -13.606 (1 / $n_{f}$ ² - 1 / n₀²) [eV]

Let's look for the energy of some levels

n $E_{n}$ (eV) $E_{nf}$ - E $E_{ni}$ (eV)

1 -13,606 E₂-E₁ = 10.20

2 -3.4015 E₃-E₂ = 1.89

3 -1.512 E₄- E₃ = 0.662

4 -0.850375

We see the lines of greatest energy for each possible series, the closest to our transition is n₁ = 3 in which a transition from infinity (n = inf) to this level has an energy of 1,512 eV that is very close to the given value

8 0

3 years ago