Reaction of sodium, lithium and potassium will be demonstrated by your instructor. why are students not allowed to handle these elements?

11. you want to calculate the displacement of an object thrown over a bridge. using -10 m/s2 for acceleration due to gravity, what would be the total displacement of the object if it took 8 seconds before hitting the water?

The a metal retainer that keeps the rolling elements evenly spaced. n a. seal n b. separator n c. bearing n d outer race

Can anybody me with this? ? (picture included.)