How many grams of nh3 are in 3.011x10^23 molecules of nh3

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 situation will produce the greatest change of momentum

What is friction? how does it affect the motion of an object?