What is the law of conservation of energy? ?

How many seconds does it take a pebble released from rest off a bridge to fall 29.4 m ? what is the pebble's speed when it has fallen 29.4 m ?

Two polarizers are oriented at 24.0∘ to one another. light polarized at a 12.0-degree angle to each polarizer passes through both. what is the transmitted intensity (%)?

Abird flies directly overhead from where you stand at an altitude of 300.0 m and at a speed horizontal to the ground of 20.0 m/s. the bird has a mass of 2.0 kg. the radius vector to the bird makes an angle \thetaθ with respect to the ground. the radius vector to the bird and its momentum vector lie in the xyxy-plane. what is the bird’s angular momentum about the point where you are standing?