[size=4]The planetary model of the atom pictures electrons orbiting the atomic nucleus much as planets orbit the Sun. In this model you can view hydrogen, the simplest atom, as having a single electron in a circular orbit 1.06 ×10−10 m in diameter. If the average speed of the electron in this orbit is known to be 2.20 x 106 m/s, calculate the number of revolutions per second it makes about the nucleus.[/size]

[size=4]Two moons, Moon X and Moon Y, have radii in the ratio of 2:3, and densities in the ratio of 3:4. What is the ratio of gravitational acceleration on Moon X to that on Moon Y?[/size]

[size=4]A rugby player passes the ball 7.00 m across the field, where it is caught at the same height as it left his hand. At what angle was the ball thrown if its initial speed was 12.0 m/s, assuming that the smaller of the two possible angles was used?[/size]

[size=4]Calculate the force a 70.0 kg high jumper must exert on the ground to produce an upward acceleration 4.00 times the acceleration due to gravity.[/size]

[size=4]A satellite is orbiting Earth and always stays above the same point on Earth’s surface. If the satellite is 42 000 km from Earth’s center, and Earth's mass is 6.0 × 10²⁴ kg, what is the approximate speed of the satellite? (Use G = 6.7 × 10−11 Nm2/kg[sup]2[/sup], for the universal gravitational constant)[/size]