Hello,
Work is done when a force causes an object to move in the same direction that the force is applied..... Friction reduces efficiency because when two surfaces slide past each other, friction resists their motion, and in real machines, some input work is always used to overcome friction.
Hope this helps!!!! Happy Holidays!!!! (:
<span>
</span>Basic Calcium Facts
Name: Calcium
Atomic Number: 20
Element Symbol: Ca
Group: 2
Period: 4
Block: s
Element Family: Alkaline Earth
Atomic Mass: 40.078(4)
Electron Configuration: [Ar]4s<span>2
</span>
Full: 1s22s22p63s23p64s2 (full)
I am pretty sure it is the most reactive elements