Several artificial satellites orbit the Earth. Table 1 lists some data for three different satellites.
| Satellite | Use | Height above Earth's surface (km) | Speed (km/s) | Period (minutes) | Revolutions per day |
|---|---|---|---|---|---|
| Tiangong | space station | 390 | 7.68 | 92.19 | 15.62 |
| Hubble | stellar observation | 540 | 7.59 | 95.35 | 15.10 |
| Sentinel | Earth observation | 810 | 7.48 |
Calculate the period of the Sentinel satellite in minutes.
[radius of the Earth=6371 km][\text{radius of the Earth} = 6371 \text{ km}][radius of the Earth=6371 km]
Calculate the number of revolutions per day for the Sentinel satellite.