What is the work done by gravity when a 2.0kg ball falls to the floor from the height of 1.50m? is it positive or negative? explain

What determines the amount of inertia an object has

The uniform slender bar rests on a smooth horizon- tal surface when a force f is applied normal to the bar at point a. point a is observed to have an initial acceleration aa of 20 m/s2, and the bar has a corre- sponding angular acceleration of 18 rad /s2. deter- mine the distance b.

How do you know how many valence electrons an atom has?