Respuesta :
Answer:
orbital speed of the moon v = 1.08 km/s
orbital speed of the moon v = 9.5 × 10² m/s
Explanation:
given data
At apogee moon distance r = 460,395 km from the earth
at perigee moon distance r = 357,643 km from the earth
solution
we consider here orbital period is 27.3 day
we get here orbital speed of the moon that is
orbital speed of the moon v = rω
orbital speed of the moon v = [tex]\frac{2\pi r}{T}[/tex] ...................1
put here value for apogee in equation 1
orbital speed of the moon v = [tex]\frac{2\pi *406395}{2358720}[/tex]
here we know 1 day = 86,400 second so 27.3 day = 2358720 seconds
orbital speed of the moon v = 1.08 km/s
and
now we put put here value for perigee in equation 1
orbital speed of the moon v = [tex]\frac{2\pi *357643*10^3}{2358720}[/tex]
orbital speed of the moon v = 9.5 × 10² m/s
We know that the centripetal force on the moon, F equals the gravitational force of attraction between the earth and moon, F'
F = mv²/r where
- m = mass of moon,
- v = orbital speed of moon and
- r = radius of orbit.
Also, F' = GMm/r² where G = 6.67 × 10⁻¹¹ Nm²/kg², M = mass of earth = 5.972 × 10²⁴ kg, m = mass of moon and r = radius of orbit
Since F = F', we have
mv²/r = GMm/r²
v² = GM/r
v = √(GM/r)
Orbital speed at apogee
The orbital speed at apogee is 990 m/s
Now, when r = radius at apogee = 406395 km = 406395000 m = 4.06395 × 10⁸ m
v = √(GM/r)
v = √(6.67 × 10⁻¹¹ Nm²/kg² × 5.972 × 10²⁴ kg/4.06395 × 10⁸ m)
v = √(39.83324 × 10¹³ Nm²/kg/4.06395 × 10⁸ m)
v = √(9.802 × 10⁵ Nm/kg)
v = √(98.02 × 10⁴ Nm/kg)
v = 9.9 × 10² m/s
v = 990 m/s
The orbital speed at apogee is 990 m/s
Orbital speed at perigee
The orbital speed at perigee is 1.06 km/s
Also, when r = radius at perigee = 357,643 km = 357643000 m = 3.57643 × 10⁸ m
v = √(GM/r)
v = √(6.67 × 10⁻¹¹ Nm²/kg² × 5.972 × 10²⁴ kg/3.57643 × 10⁸ m)
v = √(39.83324 × 10¹³ Nm²/kg/3.57643 × 10⁸ m)
v = √(11.138 × 10⁵ Nm/kg)
v = √(111.38 × 10⁴ Nm/kg)
v = 10.554 × 10² m/s
v = 1.0554 × 10³ m/s
v = 1.0554 km/s
v ≅ 1.06 km/s
The orbital speed at perigee is 1.06 km/s
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