How much weaker is the gravitational pull of the Sun on Neptune at 30 AU, than it is on Earth at 1 AU

What was the first instrument to ever record an earthquake?

How is the acceleration of an object in uniform circular motion constant? a - in magnitude only b - in direction only c - in both magnitude and direction d - in magnitude, direction & orientation

Aplane's average speed between two cities is 600 km/h. if the trip takes 2.5 hours, how far does the plane fly?