A 3.90 kg weight is placed on top of a vertical spring, which compresses a distance of 2.87 cm. Calculate the force constant (in N/m) of the spring.

stands for electromotive force and it is measured in volts. despite its name, it is not actually the force in the sense of being a "pushing" or "pulling" (not measured in newtons).an equation that relates emf,  ℰ,  to a battery's terminal voltage, v, current, i, and internal resistance, r, is    ℰ = v + irin this case, the emf can be interpreted as a voltage—a difference in electric potential.i would not say that it would be considered an energy. if emf can be defined as the energy/work per a unit charge from a battery or other electric source, then it is not strictly energy.

This  kingdom  is  made  up of species that  do  not really easily fit into other kingdoms such as the plant, animal,and  fungi  kingdom. some protists, such as the paramecium  and  amoeba, feed  on  other  organisms  while others such as algae are able to  make their own food  through the process of photosynthesis.

Blue light reflected from the ball enters human eyes.