If an atom of Calcium has 21 electrons is it a...? A) isotope

B) calcium does not have electrons

C) normal, no charge

D) ion

This question is worth 54 points ! rock falls from a ledge to the ground what energy conversion occurs during this process a potential to kinetic b kinetic to potential c thermal to mechanical d chemical to mechanical

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?

If a spring has a k value of 100 newtons per meter and it is stretched 0.50 meters, what is the restoring force of the spring?