1. Why was the discovery of Neptune a major confirmation of Newton’s universal law of gravitation? 2. Why does an astronaut have to exert a force on a weightless object to move it? 3. From the...

1. Why was the discovery of Neptune a major confirmation of Newton’s universal law of gravitation?

2. Why does an astronaut have to exert a force on a weightless object to move it?

3. From the definition KE = 1 ⁄2 mv², derive the equation KE = p²/2m, as discussed in An Astronomer’s Toolbox 2-2.