What is an example of a concentric contraction

Consider a system to be two train cars traveling toward each other. what is the total momentum of the system before the train cars collide?   kg • what must the total momentum of the system be after the train cars collide?   kg •  

Both speed and velocity measure how fast something is moving. however, since speed is not a it does not require a(n question 6 options: a) quantity , unit b) magnitude, unit c) scalar, direction d) vector, direction

Ne way in which elements differ from each other is the structure of the electron cloud in each element's atoms. in an electron cloud, an electron that is farther away from the nucleus has