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Lostsunrise [7]
3 years ago
6

During which dynasty was China first united?

Geography
1 answer:
garri49 [273]3 years ago
6 0

Answer:

During the Qin dynasty

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During which time period did most of the coal under earth’s surface begin to form?
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If significant global warming happens, the consequences will be Choose one: A. a drop in sea level. B. an interruption of ocean
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A 215 kg rocket moving radially outward from Earth has a speed of 6.42 km/s when its engine shuts off 307 km above Earth's surfa
Vinvika [58]
<h2>GIVEN DATA</h2>

Mass of Rocket = m = 215 kg

Mass of Earth = M = 5.97*10^{24} kg

Radius of Earth = R = 6.37*10^6 m

Gravitational Constant = G = 6.67*10^-11 \;\;m^3kg^{-1}s^{-2}

Speed of Rocket = 6.42 km/s

Initial Height of Rocket from Earth's Surface = 307 km = 3.07*10^5 m

Final Height of Rocket from Earth's Surface = 731 km = 7.31*10^5 m

Initial Height from Earth's Centre = R_i = 3.07*10^5 + 6.37*10^6 = 6.677*10^6 m

Final Height from Earth's Surface = R_f = 7.31*10^5 + 6.37*10^6 = 7.101*10^6 m

(a) Kinetic Energy at Final Height = K.E_f

(b) Maximum Height of Rocket above Earth's Surface = H_{max}

<h2>EXPLANATION</h2>

Part (a):

As drag air is negligible, energy will be conserved.

\therefore ΔE = 0

K.E_i + U_i = K.E_f + U_f

K.E_f = U_f - K.E_i - U_i

where, U is the potential energy of the system.

K.E_f=\;G\frac{mM}{R_f} + \frac{1}{2}mv_i^2\;-\;G\frac{mM}{R_i}\;\;\;\;----------\;(1)

Substituting Values and simplifying,

K.E_f = 3.665*10^9 J

Part (b):

The rocket will come to rest after reaching the maximum height. Therefore, its final velocity and consequently final kinetic energy will be zero.

i.e.\;\;v_f = 0\;\;\;\&\;\;\; K.E_f=0

Equation (1) will become,

0\;=\;\;G\frac{mM}{R_f} + \frac{1}{2}mv_i^2\;-\;G\frac{mM}{R_i}

or\;\;\frac{1}{2}v_i^2= GM(\frac{1}{R_i}-\frac{1}{R_f})\\\\\frac{1}{2GM}v_i^2= (\frac{1}{R_i}-\frac{1}{R_f})\\\\\therefore\; R_f = \frac{2GMR_i}{2GM-v_i^2R_i}

Substituting values and simplifying,

R_f = 10.20*10^6 m

which is the distance from the Earth's centre. To find the height of rocket from Earth's surface, we simply subtract the Earth's radius from above result.

H_{max} = R_f - R

H_{max} = 10.20*10^6\;-\;6.37*10^6\\\\H_{max} = 3.83*10^6\;\;m

4 0
3 years ago
Cuales son los recursos minerales mas importantes de asia?
vazorg [7]

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Explanation: no hay necesidad de explicar

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