How are constellations an important part of history, and what were they used for?

Crowbar of 5 metre is used to lift an object of 800 metre if the effort arm is 200cm calculate the force applied

As a pendulum bob swings back and forth several times, the maximum height it reaches becomes less and less. this is because more and more of the pendulum bob's energy is being transformed into a. heat energy b. kinetic energy c. potential energy d. kinetic energy and potential energy

Which compound is held together by the electrostatic force between two ions? a. co2 b. cci4 c. h2s d. mgf2