All categories

3 years ago

(I) A centrifuge accelerates uniformly from rest to 15,000 rpm in 240 s. Through how many revolutions did it turn in this time

Physics

1 answer:

ddd [48]3 years ago

8 0

Answer:

θ = ω0 t + 1/2 ω t^2 = 1/2 α t^2 since it starts from rest

α = (15000 / 60) / 240 = 250 / 240 = 1.04 rev/sec^2

Note that α is in rev/sec^2

T(otal) = 1/2 * 1.04 * 240^2 = 30,000 revolutions

Check:

Average RPM = (15000/2) = 7500 rev/min = 125 / sec

125 / sec * 240 sec = 30,000 rev

You might be interested in

A radio station's channel, such as 100.7 fm or 92.3 fm, is actually its frequency in megahertz (mhz), where 1mhz=106 hz and 1hz=

AURORKA [14]

The frequency of the radio station is
$f=88.7 fm= 88.7 MHz = 88.7 \cdot 10^6 Hz$

For radio waves (which are electromagnetic waves), the relationship between frequency f and wavelength $\lambda$ is
$\lambda= \frac{c}{f}$
where c is the speed of light. Substituting the frequency of the radio station, we find the wavelength:
$\lambda= \frac{3 \cdot 10^8 m/s}{88.7 \cdot 10^6 Hz}=3.38 m$

6 0

4 years ago

Read 2 more answers

A friend on skis stands still on level ground, with dry 0.00°C with a coefficient of static friction of 0.0300. How hard would y

Salsk061 [2.6K]

Answer:

20.6 N

Explanation:

Friction equals normal force times coefficient of friction.

F = Fn μ

On level ground, normal force equal weight.

Fn = W

Therefore:

F = W μ

F = (685 N) (0.0300)

F = 20.6 N

6 0

3 years ago

4. In a humidifier, air at a dry bulb temperature of 40 oC and relative humidity of 10% is humidified to a relative humidity of

lesya692 [45]

Answer:

0.0141 kg/kg.

Explanation:

So, we are given the following parameters or information from the problem above:

The relative humidity = 10% was humidified to 40%, the temperature = 40°C.

From the chart, at temperature = 40°C and relative humidity = 10%, the weight of dry air = a1 = 0.0046 kg/kg, volume = 0.89 m³/kg.

Also, from the chart at temperature = 40°C and relative humidity = 40%, the weight of dry air = a2 = 0.00187 kg/kg, volume = 0.913 m³/kg.

Therefore, the amount of moisture added in the humidifier per kg of dry air = 0.0046 kg/kg - 0.00187 kg/kg = 0.0141 kg/kg.

8 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

The electric potential at a distance of 4 m from a certain point charge is 200 V relative to infinity. What is the potential (re

lakkis [162]

Answer:

400 volt

Explanation:

$v \: = \: \frac{kq}{r}$

since the charge is constant

V1*r1 = V2*r2

V2 = V1r1/r2

= (200×4) ÷ 2

= 800/2

= 400 Volt

4 0

4 years ago