Final answer:
An object attached to a spring on a frictionless surface is known as a simple harmonic oscillator, exhibiting motion defined by Hooke's law. The spring's stiffness and the object's mass determine the motion's period.
Step-by-step explanation:
An object attached to a coiled spring that is sliding on a frictionless surface is called a simple harmonic oscillator. When the object is displaced from its equilibrium position, it will perform simple harmonic motion with a certain amplitude (X) and period (T). The maximum speed of the object is reached as it crosses the equilibrium position. According to Hooke's law, the stiffness of the spring influences the period of oscillation; a stiffer spring leads to a smaller period (T), while a massier object leads to a larger period (T).
The concept described is fundamentally different from a simple pendulum, which consists of a mass hanging from a string where the motion is due to the restoring force of gravity. The terms projectile motion and mass on a string also refer to different physical phenomena and are not related to an object attached to a spring performing simple harmonic motion as described by Hooke's law.