A spring, of spring constant k, is compressed by distance di, and when released pushes a block of mass m forward across a frictionless, horizontal surface. The block collides with another identical block which was initially at rest, and the two blocks stick together. What is the final speed of the combined system? A. di√2
B. di√k/2m
C. 2di√k/m
D. di/2√k/m

adding a(n) to an electric circuit would increase the magnetic field around a wire;

b. solenoid

a solenoid is a type of electromagnet whose purpose is to generate a controlled magnetic field.

if the purpose of the solenoid is instead to impede changes in the electric current, a solenoid can be more specifically classified as an inductor rather than an electromagnet.

conservation of mass

mass before something happens = mass afterwards