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n200080 [17]
3 years ago
8

A school custodian waxed a gymnasium floor that measured 20 feet by 20 feet. How many square feet did she have to wax?

Physics
1 answer:
Vadim26 [7]3 years ago
5 0
We have to calculate how many square feet a school custodian has to wax and to choose the correct answer. A gymnasium floor is in the shape of the square ( 20 by 20 feet ). The area of the square is : A = L^2. For L = 20 ft, A = 20^2 = 20 * 20 = 400 ft^2. Answer: <span>D. 400 square feet.</span>
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Words that describe direction east, up, and left is it true or false
m_a_m_a [10]

Answer:

True

Explanation:

East, up, and left all define as a direction.

7 0
3 years ago
Read the following questions and answer them using complete sentences. Be sure to fully explain your answers.
astra-53 [7]

Wave power can be regarded as a reliable source of energy because the ocean currents are always moving.

<h3>What can be the challenges of wave power?</h3>

Wave power is a device that can be used to convert the mechanical energy of the ocean waves into electrical energy based on the principle of conservation of energy.

The major challenges that face the use of wave power in electricity generation is the unreliability of the waves which leads to uncertainty in the quantity of power generated Also, the wave direction and direction of ocean currents all limit the amount of power generated by this method. However, in spite of challenges, it can be regarded as a reliable source of energy because the ocean currents are always moving.

Learn more about wave power:brainly.com/question/1362067

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6 0
1 year ago
A Michelson interferometer uses red light with a wavelength of 656.45 nm from a hydrogen discharge lamp. Part A How many bright-
kati45 [8]

Answer:

51793 bright-dark-bright fringe shifts are observed when the mirror M2 moves through 1.7cm

Explanation:

The number of maxima appearing when the mirror M moves through distance \Delta L is given as follows,

\Delta m = \frac{\Delta L}{\frac{\lambda}{2}}

Here,

\Delta L= is the distance moved by the mirror M

\lambda is the wavelenght of the light used.

\Delta L= 0.017m

\lambda = 656.45*10^{-9}m

\Delta m = \frac{0.017}{\frac{656.45*10^{-9}}{2}}

\Delta m = 51793.72

Therefore, 51793 bright-dark-bright fringe shifts are observed when the mirror M2 moves through 1.7

3 0
3 years ago
Compare the numbers of protons and electrons in a positive ion with the numbers of protons and electrons in a negative ion.
kow [346]

Answer:

In a positive ion, the number of protons is larger than the number of electrons.

In a negative ion, the number of protons is smaller than the number of electrons.

Explanation:

Each proton carries a positive charge of one unit.

Each elec in tron carries a negative charge of one unit.

In an atom, there are as many protons as electrons. Hence, they are neutral.

However, in a positive ion, there are less negative charge than positive charge. Hence the net charge is positive. That also means that there are fewer negatively-charged electrons than positively-charged protons.

Similarly, in a negative ion, there are more negative charge than positive charge. Hence the net charge is negative. That also means that there are more negatively-charged electrons than positively-charged protons.

6 0
3 years ago
A water tower is a familiar sight in many towns. The purpose of such a tower is to provide storage capacity and to provide suffi
Mademuasel [1]

The image of the water tower and the houses is in the attachment.

Answer: (a) P = 245kPa;

(b) P = 173.5 kPa

Explanation: <u>Gauge</u> <u>pressure</u> is the pressure relative to the atmospheric pressure and it is only dependent of the height of the liquid in the container.

The pressure is calculated as: P = hρg

where

ρ is the density of the liquid, in this case, water, which is ρ = 1000kg/m³;

When it is full the reservoir contains 5.25×10⁵ kg. So, knowing the density, you know the volume:

ρ = \frac{m}{V}

V = ρ/m

V = \frac{5.25.10^{5}}{10^{3}}

V = 525 m³

To know the height of the spherical reservoir, its diameter is needed and to determine it, find the radius:

V = \frac{4}{3}.\pi.r^{3}

r = \sqrt[3]{ \frac{3}{4\pi } .V}

r = \sqrt[3]{\frac{525.3}{4\pi } }

r = 5.005 m

diameter = 2*r = 10.01m

(a) Height for House A:

h = 15 + 10.01

h = 25.01

P = hρg

P = 25.01.10³.9.8

P = 245.10³ Pa or 245kPa

(b) h = 25 - 7.3

h = 17.71

P = hρg

P = 17.71.1000.9.8

P = 173.5.10³ Pa or 173.5 kPa

4 0
3 years ago
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