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alukav5142 [94]
2 years ago
13

Find a numerical value for rhoearth, the average density of the earth in kilograms per cubic meter. Use 6378km for the radius of

the earth, G=6.67×10−11m3/(kg⋅s2), and a value of g at the surface of 9.80m/s2.Express your answer to three significant figures.
Physics
1 answer:
mylen [45]2 years ago
8 0

Answer:

density = 5520 kg/m^3

Explanation:

given that

radius of earth = 6378 km

G = 6.67 x 10⁻¹¹ m³/kg.s²

g = 9.80 m/s²

we know,

g = \dfrac{GM}{r^2}

mass of earth

M = \dfrac{gr^2}{G}

M = \dfrac{9.8 \times (6378 \times 10^3)^2}{6.67 \times 10^{-11}}

M = 5.972 x 10²⁴ kg

density =\dfrac{mass}{volume}

V = volume of the earth = 4/3πr³

V = 4/3 x 3.14 x (6378  x 10³)³

V = 1.08 x 10²¹ m³

density = \dfrac{5.972\times 10^{24}}{1.08\times 10^{21}}

density = 5.52 x 10³  kg/m^3

density = 5520 kg/m^3

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A "moving sidewalk" in an airport terminal moves at 1.0 m/s and is 35.0 m long. If a woman steps on at one end and walks at 1.5
pishuonlain [190]

Answer:

a.14 s

b.70 s

Explanation:

a.Let the sidewalk moving in positive x- direction.

Speed  of sidewalk relative to ground=v_s=1m/s

Speed of women relative to sidewalk=v=1.5m/s

The speed of women relative to the ground

v_w=v_s+v=1+1.5=2.5m/s

Distance=35 m

Time=\frac{distance}{speed}

Using the formula

Time taken by women to reach the opposite end if she walks in the same direction the sidewalk is moving=\frac{35}{v_w}=\frac{35}{2.5}=14s

b.If she gets on at the end opposite the end in part (a)

Then, we take displacement negative.

Speed  of sidewalk relative to ground=v_s=1m/s

Speed of women relative to sidewalk=v=-1.5 m/s

The speed of women relative to the ground=v_w=v_s+v=1-1.5=-0.5m/s

Time=\frac{-35}{-0.5}=70 s

Hence, the women takes 70 s to reach the opposite end if she walks in the opposite direction the sidewalk is moving.

3 0
3 years ago
If it takes Ashley 10 seconds to run from the batter's box to first base at an average speed
abruzzese [7]

Answer:

65 meters

Explanation:

Time = 10 seconds

Speed = 6.5 m/s

Distance = ?

Distance = speed\times time\\\\d = 6.5 \times 10 \\d = 65 m

7 0
3 years ago
Which of the following statements accurately describes the properties of gases?
Ray Of Light [21]
<span>A change in the pressure of a gas results in a more significant change in volume than it would in a liquid.  is the statement that accurately describes the property of gas. Gas only depends on how you store it. the bigger the space the wider gas can expand, the smaller the space, the more compress the gas can become.</span>
4 0
3 years ago
Read 2 more answers
Because of your success in physics class you are selected for an internship at a prestigious bicycle company in its research and
tiny-mole [99]

To develop the problem it is necessary to apply the equations related to the moment of inertia.

The given values can be defined as,

M = 1.0 kg

r = 0.5 m

m = 10 g

I = 0.280 kg.m^2

According to the definition of the moment of inertia applied to the exercise we can arrive at the equation that,

I = I_{rim} + n * I_{spoke}

Where n is the number of spokes necessary to construct the wheel.

I_{rim} = M*r^2 = 1.0 * 0.5^2

I_{spoke} = \frac{1}{3} * m * r^2 = \frac{1}{3}* 10 * 10^-3 * 0.5^2

Replacing the values at the general equation we have,

0.280 = 1.0 * 0.5^2 + n * (1/3 * 10 * 10^-3 * 0.5^2 )

Solving for n,

n = 36

Therefore the number of spokes necessary to construct the wheel is 36

PART B) The mass of the wheel is given by the sum of all masses and the total spokes, then

M_w= M + n*m

M_w = 1.0 + 36* 10 * 10^{-3} Kg

M_w = 1.36 Kg

Therefore the mass of the wheel must be of 1.36Kg

4 0
3 years ago
.In a bizarre but harmless accident, Superman fell from the top of the Eiffel Tower. How fast was Superman traveling when he hit
ELEN [110]

Answer:

 (7.8) x (9.8 m/s)  =  76.44 m/s

during the time he spent falling.

Since his falling speed was zero when he 'stepped' off of the top,

he hit the ground at  76.44 m/s.

That's about 170 miles per hour.

I'll bet he left one serious crater!

I hope this helps too! :D

Explanation:

4 0
3 years ago
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