The density of a earth is given by p=3g/4πRG, where R is radius of earth G is gravitational constant. check the dimensional consistency of this relation

Aball tossed vertically upward from the ground next to a building passes the bottom of a window 1.8 s after being tossed and passes the top of the window 0.20 s later. the window is 2.0 m high from top to bottom. what was the ball's initial velocity? the unit vector j^ is directed upward. how far is the bottom of the window from the launch position? how high does the ball rise above the launch position?

Which best represents the law of conservation of mass ?

Because light travels in a straight line and casts a shadow, isaac newton hypothesized that light is