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3 years ago

5

Relating to Newton’s Third Law, action and reaction, what is the reaction when a rocket expels gas, smoke and flames from the no

zzle end of the rocket engine?

1 answer:

Cloud [144]3 years ago

7 0

Answer:

Propels in the opposite direction

Explanation:

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Two Earth satellites, A and B, each of mass m, are to be launched into circular orbits about Earth's center. Satellite A is to o

Pachacha [2.7K]

(a) 0.448

The gravitational potential energy of a satellite in orbit is given by:

$U=-\frac{GMm}{r}$

where

G is the gravitational constant

M is the Earth's mass

m is the satellite's mass

r is the distance of the satellite from the Earth's centre, which is sum of the Earth's radius (R) and the altitude of the satellite (h):

r = R + h

We can therefore write the ratio between the potentially energy of satellite B to that of satellite A as

$\frac{U_B}{U_A}=\frac{-\frac{GMm}{R+h_B}}{-\frac{GMm}{R+h_A}}=\frac{R+h_A}{R+h_B}$

and so, substituting:

$R=6370 km\\h_A = 5970 km\\h_B = 21200 km$

We find

$\frac{U_B}{U_A}=\frac{6370 km+5970 km}{6370 km+21200 km}=0.448$

(b) 0.448

The kinetic energy of a satellite in orbit around the Earth is given by

$K=\frac{1}{2}\frac{GMm}{r}$

So, the ratio between the two kinetic energies is

$\frac{K_B}{K_A}=\frac{\frac{1}{2}\frac{GMm}{R+h_B}}{\frac{1}{2}\frac{GMm}{R+h_A}}=\frac{R+h_A}{R+h_B}$

Which is exactly identical to the ratio of the potential energies. Therefore, this ratio is also equal to 0.448.

(c) B

The total energy of a satellite is given by the sum of the potential energy and the kinetic energy:

$E=U+K=-\frac{GMm}{R+h}+\frac{1}{2}\frac{GMm}{R+h}=-\frac{1}{2}\frac{GMm}{R+h}$

For satellite A, we have

$E_A=-\frac{1}{2}\frac{GMm}{R+h_A}=-\frac{1}{2}\frac{(6.67\cdot 10^{-11})(5.98\cdot 10^{24}kg)(28.8 kg)}{6.37\cdot 10^6 m+5.97\cdot 10^6 m}=-4.65\cdot 10^8 J$

For satellite B, we have

$E_B=-\frac{1}{2}\frac{GMm}{R+h_B}=-\frac{1}{2}\frac{(6.67\cdot 10^{-11})(5.98\cdot 10^{24}kg)(28.8 kg)}{6.37\cdot 10^6 m+21.2\cdot 10^6 m}=-2.08\cdot 10^8 J$

So, satellite B has the greater total energy (since the energy is negative).

(d) $-2.57\cdot 10^8 J$

The difference between the energy of the two satellites is:

$E_B-E_A=-2.08\cdot 10^8 J-(-4.65\cdot 10^8 J)=-2.57\cdot 10^8 J$

4 0

3 years ago

Is cold fusion science or pseudoscience

kondor19780726 [428]

The experiments that claimed to demonstrate cold fusion were found
to have been faulty by others who reviewed them. Also, nobody else
was able to reproduce the finding in other laboratories. In the world
of Science, this pretty much says that the initial claims were unfounded.

5 0

3 years ago

A bike accelerates uniformly(from rest to a speed of 7 m/s over a distance of 40 m. Determine

marshall27 [118]

Answer:

$0.61 m/s^2$

Explanation:

The bike's acceleration can be found by using the following suvat equation:

$v^2-u^2=2as$

where

v is the final velocity of the bike

u is the initial velocity

a is the acceleration

s is the distance covered

For the bike in the problem,

u = 0

v = 7 m/s

d = 40 m

Solving the equation for a, we find the acceleration:

$a=\frac{v^2-u^2}{2s}=\frac{7^2-0}{2(40)}=0.61 m/s^2$

3 0

3 years ago

Measurement conversions [metric to metric] 568 cm = m

Trava [24]

Answer:

5.68 meters

Explanation:

hope this helps!

7 0

3 years ago

parallel-plate capacitor is made of two square plates 25 cm on a side and 1.0 mmapart. The capacitor is connected to a 50.0-V ba

noname [10]

Answer:

6.9 x 10^-7 J

3.5 x 10^-7 J

Explanation:

<u>Identify the unknown: </u>

The energies stored in the capacitor before and after the plates are pulled farther apart

<u>List the Knowns: </u>

Voltage of the battery: V = 50 V

Area of the plates: A = 0.25 x 0.25 = 0.0625 m^2

Original distance between the plates: d = 1 mm = 10^-3 m

New distance between the plates: d = 2 mm = 2 x 10^-3 m

Permittivity of free space: ∈o = 8.85 x 10^-12 C^2/Nm^2-

<u>Set Up the Problem: </u>

Capacitance of a parallel-plate capacitor:

C=∈o*A/d

Energy stored in a capacitor:

U_c=(1/2)*V^2*C

<u>Solve the Problem: </u>

<u>Before the plates are pulled farther apart: </u>

C = 8.85 x 10^-12 x 0.0625/10^-3 = 5•53 x 10^-10 F

U_c = (1/2) x (50)^2 x 5.53 x 10^-10= 6.9 x 10^-7 J

<u>After the plates are pulled farther apart: </u>

C = 8.85 x 10^-12 x 0.0625/2*10^-3 = 2•77 x 10^-10 F

U_c = (1/2) x (50)^2 x 2•77 x 10^-10 = 3.5 x 10^-7 J

The energy decrease because the capacitance decrease, so the stored charge decrease and transferred to the battery

3 0

3 years ago