I'm pretty sure there is only one element named after Mendeleev: <span>Mendelevium.</span>
An isotope is one of the forms of an element that has the same number of protons, but a different number of neutrons.
When people aboard a plane...the amount of baggage you take has to vary because the plane has a certain carrying capacity.
Answer:

Explanation:
From the law of conservation of energy
Energy lost by the spring, W=Kinetic energy gained, KE+Potential energy gained, PE+Work done by friction, Fr



The required distance from A to B is 
Concrete is not a polymer which Nylon, and Kevlar are