The blocks are forced together, compressing a spring between them by a distance x; (the force constant of the spring is k) then the system is released from rest on a level, frictionless surface. The spring, which has negligible mass, is not fastened to either block and drops to the surface after it has expanded. What is the speed that block A acquired, vA

   v =    x

Explanation:

For this exercise let's use the important topic of conservation of energy

starting point. Spring compression point

          Em₀ = K_e = ½ k x²

final point. When the spring is not compressed

          Em_f = K = ½ m v²

as they indicate that there is no friction, the energy is conserved

          Em₀ = Em_f

          ½ k x² = ½ m v²

          v =    x

current and voltage can both be different in different parts of a circuit so it matters where you place the ammeter and voltmete

what is the speed of a softball that travels 20m in 2secs

speed = 20/2 = 10 m/s