With what force does the concrete act back on the sledgehammer during the impact?.

a and b sometimes have a positive value

i am pretty sure it is c because when people are closer together, they cannot move as freely. picture being in a mostly full elevator, for instance. the people are right next to you, and you can barely move.

answer

procedural programming, object-oriented programming

explanation

procedural programming is a type of computer programming language that specifies a series of well structured steps and procedures   within its development period of time. it contains a systematic order of statements, functions and commands to complete a computational task or program. it is centered on creating procedures. while object oriented programming is a programming language that is centered on creating objects rather that actions and data rather than logic.. it has four principles which are inheritance, polymorphism, abstraction and encapsulation