Hi guys please help me what is the chemical formula of potassium react with oxygen

A person standing on a scale feels a normal force of 655 N pushing up on him. What is his mass? (Unit=kg)

dimulka [17.4K]

Answer:

Approximately 66,8kg

Hope this help :D

Explanation:

F=mg. So 655N= 9.8 m/s² × mass.

Mass = 655 / 9.8

3 0

3 years ago

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Physics question 28 plz help me

Alexus [3.1K]

Answer:

a. I = 30 A

b. E = 1080000 J = 1080 KJ

c. ΔT = 12.86°C

d. Cost = $ 4.32

Explanation:

a.

The current in the coil is given by Ohm's Law:

$V = IR\\I = \frac{V}{R}$

where,

I = current = ?

V = Voltage = 120 V

R = Resistance = 4 Ω

Therefore,

$I = \frac{120\ V}{4 \Omega}\\$

I = 30 A

b.

The energy can be calculated as:

$E = VIt\\E = (120\ V)(30\ A)(5\ min)(\frac{60\ s}{1\ min})\\$

E = 1080000 J = 1080 KJ

c.

For the increase in the temperature of water:

$E = mC\Delta T\\$

where,

m = mass of water = 20 kg

C = specific heat of water = 4.2 KJ/kg.°C

Therefore,

$1080\ KJ = (20\ kg)(4.2\ KJ/kg.^oC)\Delta T$

ΔT = 12.86°C

d.

First, we will calculate the total energy consumed:

$E=(Power)(Time)\\E=VI(Time)\\E = (120\ V)(30\ A)(0.5\ h/d)(30\ d)\\E = 54000\ Wh\\E = 54 KWh$

Now, for the cost:

$Cost = (Unit\ Cost)(Energy)\\Cost = (\$ 0.08\KWh)(54\ KWh)$

Cost = $ 4.32

7 0

3 years ago

Two particles are fixed to an x axis: particle 1 of charge q1 = 2.78 × 10-8 c at x = 15.0 cm and particle 2 of charge q2 = -3.24

Oksi-84 [34.3K]

Refer to the attached figure. Xp may not be between the particles but the reasoning is the same nonetheless.
At xp the electric field is the sum of both electric fields, remember that at a coordinate x for a particle placed at x' we have the electric field of a point charge (all of this on the x-axis of course):
$E=\frac{1}{4\pi\varepsilon_0}\frac{q}{(x-x')^2}$
Now At xp we have:
$\frac{1}{4\pi\varepsilon_0}\frac{q_1}{(x_p-x_1)^2}-\frac{1}{4\pi\varepsilon_0}\frac{3.29q_1}{(x_p-x_2)^2}=0$
$\implies (x_p-x_1)^2=\frac{(x_p-x_2)^2}{3.29}\\
\implies(1-\frac{1}{3.29})x_p^2+2(\frac{x_2}{3.29}-x_1)x_p+x_1^2-\frac{x_2^2}{3.29}=0$
Which is a second order equation, using the quadratic formula to solve for xp would give us:
$xp=\frac{-(\frac{x_2}{3.29}-x_1)-\sqrt{(\frac{x_2}{3.29}-x_1)^2-(1-\frac{1}{3.29})(x_1^2-\frac{x_2^2}{3.29})}}{(1-\frac{1}{3.29})}$
or
$xp=\frac{-(\frac{x_2}{3.29}-x_1)+\sqrt{(\frac{x_2}{3.29}-x_1)^2-(1-\frac{1}{3.29})(x_1^2-\frac{x_2^2}{3.29})}}{(1-\frac{1}{3.29})}$
Plug the relevant values to get both answers.
Now, let's comment on which of those answers is the right answer. It happens that BOTH are correct. This is simply explained by considring the following.

Let's place a possitive test charge on the system This charge feels a repulsive force due to q1 but an attractive force due to q2, if we place the charge somewhere to the left of q2 the attractive force of q2 will cancel the repulsive force of q1, this translates to a zero electric field at this x coordinate. The same could happen if we place the test charge at some point to the right of q1, hence we can have two possible locations in which the electric field is zero. The second image shows two possible locations for xp.

6 0

4 years ago

When light goes from one material into another material having a HIGHER index of refractionA) its speed decreases but its wavele

Mnenie [13.5K]

Answer:

E) its speed and wavelength decrease, but its frequency stays the same

Explanation:

First of all, the frequency of a light wave does not depend on the medium, while wavelength and speed do. Therefore, the frequency remains costant.

In particular, the speed of light in a medium is given by:

$v=\frac{c}{n}$

where c is the speed of light in a vacuum and n is the index of refraction. From the formula, we see that v and n are inversely proportional: so, when the light moves into a material with higher index of refraction, its speed decreases.

Moreover, speed is related to wavelength by

$v=\lambda f$

where $\lambda$ is the wavelength and f is the frequency. Since the two quantities are directly proportional, this means that since the speed decreases, the wavelength decreases as well.

So, the correct choice is

E) its speed and wavelength decrease, but its frequency stays the same

5 0

3 years ago

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A clever inventor claims to be able to make an electric car that makes its own electricity and never needs gas. The inventor cla

sergeinik [125]

Answer:

Yes, it would work.

Explanation:

From Flehmings left hand rule, current can be generated when a coil cuts the magnetic field of a powerful magnet. Thus, the spin of properller turns a generator thereby converts motion to electrical energy.

The major challenge would be how to set the car in motion when at rest. But this can be solved by energy consrvation process. The law of conservation of energy states that energy cannot be created or destoyed, but transformed from one form to another. Thus, there would be mechanism having a device called an inverter which stores electric energy when the vehicle is in motion. This regenerates the required initial energy to set the electric car in motion when at rest or stops.

4 0

4 years ago

Hi guys please help me what is the chemical formula of potassium react with oxygen ​

Hi guys please help me what is the chemical formula of potassium react with oxygen