In the chapters dedicated to kinematic analysis of mechanisms (i.e., Chaps. 2 , 3 , 4 , 5 , 6 , 7 , 8 and 9 ), attention was focused on calculating quantities like position, velocity, and acceleration, but no forces or moments were taken into consideration (motions without forces). In the static analysis (Chaps. 10 and 11 ), forces were included in the analysis, but accelerations were assumed to be zero or negligible (forces without motions). While statics can sometimes provide good first estimations for the solution of dynamic problems, there are many cases like resonance (in vibrations) where dynamic effects play the dominant role and cannot be ignored. In this chapter, dynamic problems in which neither accelerations nor forces are negligible are considered and the full kinetic problem is solved (forces together with motions). Chapter 12 is the first one of the four chapters that are dedicated to the kinetic analysis of machines and mechanisms. In this chapter, a brief review of planar dynamics is presented and the three main solution methods, i.e., Newton’s second law, impulse and momentum, and work and energy are briefly reminded.