Let's carefully examine Sid's chart and the possible answers to determine the error correctly.
1. Tangential Speed:
- Sid's description:
- Remains constant throughout orbit.
- Decreases with satellite's increasing distance from Earth.
There is nothing inherently wrong with this description. In a circular orbit, the tangential speed does indeed remain constant. In an elliptical orbit, this observation is also valid where the speed is highest at the perigee (closest point to Earth) and lowest at the apogee (farthest point from Earth).
2. Centripetal Force:
- Sid's description:
- Parallel to the velocity of the satellite.
- Does not speed up or slow down the satellite.
Here, we can identify the mistake. The centripetal force, by definition, should always be perpendicular to the velocity of the satellite, pointing towards the center of the satellite's circular path (towards Earth). This force is what keeps the satellite in orbit, changing its direction, and not its speed. "Parallel to the velocity" is incorrect and fundamentally misunderstands the nature of centripetal force.
3. Centripetal Acceleration:
- Sid's description:
- Always points toward Earth.
- Exists because the satellite is always changing direction.
This description is correct. Centripetal acceleration must always point toward the center of the circular path (toward Earth in this case) because it is constantly changing the direction of the satellite's velocity, keeping it in orbit.
Now, let's match Sid's possible errors with the given choices:
- Tangential speed changes throughout a satellite's orbit: This is not correct as a general statement. As mentioned, tangential speed remains constant in a circular orbit but changes in an elliptical one. Sid did not make a mistake here explicitly according to the descriptions.
- Centripetal force is perpendicular to the velocity of the satellite: This is, indeed, the correct description of the centripetal force. Sid inaccurately described it as parallel.
- Tangential speed increases with a satellite's increasing distance from Earth: This option is incorrect as the tangential speed actually tends to decrease with increasing distance in an elliptical orbit due to gravitational influence. Sid did not make this error.
- Centripetal force can sometimes slow down a satellite in orbit: This statement is not correct. The centripetal force cannot change the speed of the satellite; it only changes the direction of its motion. This is not the error Sid made.
Thus, the correct description of Sid's error is:
Centripetal force is perpendicular to the velocity of the satellite.
