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3 years ago

A 15,000 kg satellite is orbiting at 800 km above the Earth’s surface. What is the potential energy of the satellite?

Engineering

1 answer:

vredina [299]3 years ago

6 0

Answer:

$-8.34\times 10^{11}\ \text{J}$

Explanation:

m = Mass of satellite = 15000 kg

h = Distance above Earth = 800 km

R = Radius of Earth = 6371 km

M = Mass of Earth = $5.972\times 10^{24}\ \text{kg}$

G = Gravitational constant = $6.674\times 10^{-11}\ \text{Nm}^2/\text{kg}^2$

Potential energy is given by

$U=-\dfrac{GMm}{R+h}\\\Rightarrow U=-\dfrac{6.674\times 10^{-11}\times 5.972\times 10^{24}\times 15000}{(6371+800)\times 10^3}\\\Rightarrow U=-8.34\times 10^{11}\ \text{J}$

The potential energy of the satellite is $-8.34\times 10^{11}\ \text{J}$ .

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Consider the gas carburizing of a gear of 1018 steel (0.18 wt %) at 927°C (1700°F). Calculate the time necessary to increase the

Artyom0805 [142]

Answer:

t = 56.6 min

Explanation:

Fick's second law is used to calculate time required for diffusion

$\frac{C_s - C_x}{C_s - C_o} = erf( \frac{x}{2\sqrt{Dt}})$

where

$C_s$ = 1.15%

$C_o$ = 0.18%

$C_x$ = 0.35%

x = 0.40 mm = 0.0004 n

$D_{927^O\ C } = 1.28\times 10^{11} m^2/s$

therefore we ahave

$\frac{1.15-0.35}{1.15- 0.18} = erf[\frac{4\times 10^{-4}}{2\sqrt{1.28\times 10^{-11} t}}]$

$0.8247 = erf [\frac{55.90}{\sqrt{t}}] = erf z$

from error function table we hvae following result

for erf z z

0.8209 0.95

0.8247 x

0.8427 1

therefore

$\frac{0.8247 - 0.8209}{0.8427 - 0.8209} = \frac{x - 0.95}{1 - 0.95}$

x = 0.959

thus

$z = \frac{55.90}{\sqrt{t}}$

$0.959 = \frac{55.90}{\sqrt{t}}$

t = 56.6 min

5 0

3 years ago

Please Help !!

Alla [95]

Answer:

how are we supposed to help?

4 0

3 years ago

A cubic transmission casing whose side length is 25cm receives an input from the engine at a rate of 350 hp. If the vehicle's ve

Musya8 [376]

Answer:

The surface temperature is 921.95°C .

Explanation:

Given:

a=25 cm ,P=350 hp⇒P=260750 W

Power transmitted $0.95\times 260750$ W and remaining will lost in the form of heat.This heat transmitted to air by the convection.

h=230 $\frac{W}{m^2-K},\eta =0.95$

Actually heat will be transmit by the convection.

In convection Q=hA $\Delta T$

So $P=\Delta T\times Q$

$0.05\times 260750=230\times0.25^2\(T-15)$

T=921.95°C

So the surface temperature is 921.95°C .

6 0

3 years ago

A 20.0 µF capacitor is charged to a potential difference of 800 V. The terminals of the charged capacitor are then connected to

Sergeu [11.5K]

Answer:

a) Q_initial = 16 * 10^-3 C

b) V_1 = V_2 = (16/3) * 10^2 V

c) E = 64/15 J

d) dE = 32/15 J of decrease

Explanation:

Given:

- Capacitor 1, C_1 = 20.0 uF

- Capacitor 2, C_2 = 10.0 uF

- Charged with P.d V = 800 V

Find:

a) the original charge of the system,

(b) the ﬁnal potential difference across each capacitor

(d) the decrease in energy when the capacitors are connected.

Solution:

- The initial charge in the circuit is the one carried by the first charged capacitor.

Q_initial = C_1*V

Q_initial = 20*10^-6 * 800

Q_initial = 16 * 10^-3 C

- After charging the other capacitor, we know that the total charge is conserved among two capacitor:

Q_initial = Q_1 + Q_2

- We also know that potential difference across two capacitor is also same.

V_1 = V_2 = Q_1 / C_1 = Q_2 / C_2

- Using the two equations and solve for charge Q_2:

Q_2 = Q_1*C_2/C_1

Q_2 = Q_1*10/20 = 0.5*Q_1

- using conservation of charge:

Q_initial = 1.5*Q_1

Q_1 = 16*10^-3 / 1.5 = 10.67*10^-3 C

- Hence the Voltage across each capacitor is:

V_2 = V_1 = Q_1 / C_1

= 10.67*10^-3 / 20*10^-6

= (16/3) * 10^2 V

- The energy in the system is:

E = 0.5*C_eq*V^2

Where, C_eq is the equivalent capacitance of paralle circuit.

E = 0.5*(20+10)*10^-6 *((16/3) * 10^2)^2

E = 64/15 J

- The decrease in energy of the capacitors is:

dE = E_initial - E_final

Where, E_initial is due to charging of the C_1 only:

dE = 0.5*10^-6*20*800^2 - (64/15)

dE = 32/5 - 64/15 = 32/15 J

5 0

3 years ago

1. The construction process begins with which of the following stages?

Firdavs [7]

Answer:

c) site preparation

Explanation:

A construction process can be defined as a series of important physical events (processes) that must be accomplished during the execution of a construction project.

Generally, in the construction of any physical asset such as offices, hospitals, schools, stadiums etc, the first step of the construction process is site preparation. Site preparation refers to processes such as clearing, blasting, levelling, landfilling, surveying, cutting, excavating and demolition of all unwanted objects on a piece of land, so as to make it ready for use.

This ultimately implies that, site preparation should be the first task to be accomplished in the construction process.

Hence, the construction process typically begins with site preparation before other activities such as the laying of foundation can be done.

Additionally, construction costs can be defined as the overall costs associated with the development of a built asset, project or property. The construction costs is classified into two (2) main categories and these are; capital and operational costs.

7 0

3 years ago