Hel plzz I'm confused If the acceleration due to gravity is 9.8 m/s^2 and you drop a rock off the top of a building. It takes 4.5 s to hit the ground. How tall is the building?​

Considering only the earth's rotation, determine how much later the asteroid would have had to arrive to put the explosion above helsinki at longitude 25˚ e? this would have obliterated the city.

Most short-period comets do not have randomly oriented orbits because

When is a current produced? when the terminals of an electrochemical cell are connected by a wire if the electric circuit is opened in an electrochemical cell if the electrolyte is removed from an electrochemical cell when the electrodes are reversed in an electrochemical cell