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Zorluk: OrtaGravitational Field and Orbits

Two satellites, XX and YY, move in circular orbits around a planet with orbital radii of rr and 4r4r, respectively. If satellite XX travels at an orbital speed of vv, what is the orbital speed of satellite YY?

  1. v2\frac{v}{2}Cevap
  2. B
    v4\frac{v}{4}
  3. C
    2v2v
  4. D
    4v4v

Cevap

The orbital speed of satellite YY is v2\frac{v}{2}.
The orbital speed vv of a satellite in a circular orbit of radius rr around a planet of mass MM is given by v=GMrv = \sqrt{\frac{GM}{r}}. When the radius increases by a factor of 4 from rr to 4r4r, the new speed becomes vY=GM4r=12GMr=v2v_Y = \sqrt{\frac{GM}{4r}} = \frac{1}{2} \sqrt{\frac{GM}{r}} = \frac{v}{2}.

Adım Adım Çözüm

1
Write the formula for orbital speed of a satellite
v=GMrv = \sqrt{\frac{GM}{r}}
Orbital speed depends on the gravitational mass MM of the central body and the orbital radius rr.
2
Set up the ratio between the orbital speeds of satellites YY and XX
vYvX=rXrY\frac{v_Y}{v_X} = \sqrt{\frac{r_X}{r_Y}}
Since GG and MM are constant, orbital speed is inversely proportional to r\sqrt{r}.
3
Substitute the given values rX=rr_X = r, rY=4rr_Y = 4r, and vX=vv_X = v
vY=vr4r=v14=v2v_Y = v \sqrt{\frac{r}{4r}} = v \sqrt{\frac{1}{4}} = \frac{v}{2}
Evaluating the square root yields a factor of 12\frac{1}{2}.

Anahtar Kavram

Orbital Speed of a Satellite
Tahmini Süre:1m 0s
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