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As background for this problem, review Conceptual Example 6. A 7460 kg satellite

ID: 1904536 • Letter: A

Question

As background for this problem, review Conceptual Example 6. A 7460 kg satellite has an elliptical orbit, as in Figure 6.9b. The point on the orbit that is farthest from the earth is called the apogee and is at the far right side of the drawing. The point on the orbit that is closest to the earth is called the perigee and is at the far left side of the drawing. Suppose that the speed of the satellite is 2850 m/s at the apogee and 8550 m/s at the perigee. Figure 6.9b (a) Find the work done by the gravitational force when the satellite moves from the apogee to the perigee. J (b) Find the work done by the gravitational force when the satellite moves from the perigee to the apogee. J

Explanation / Answer

Kinetic energy at apogee:

KE(apogee) = 0.5*7460*2850^2

= 3.03*10^10 J

Kinetic energy at perigee:

KE(perigee) = 0.5*7460*8550^2

= 2.727*10^11 J

(a)

Work(gravitational Force) = 2.727*10^11 -  3.03*10^10

=2.424*10^11 J

(b)

Work(gravitational Force) = -2.727*10^11 + 3.03*10^10

= -2.424*10^11 J