Why is kinetic friction less than static friction?

How do you calculate velocity of a box attached to a spring? What happens to most of the energy from the breakdown of food? The energy an object has because of its motion is called potential energy? What did classical physics predict would happen to the light given off by an object as its temperature increased? How did the phonograph cylinder work? How much pressure does it take to break one strip of duct tape? What is the relationship between height and energy? How fast is Africa moving and in what direction? What color is a ghost? Who much does a pig weigh in kilograms? Physics- What is the frequency of ultraviolet light that has a wavelength of 300 nm? What happens to light if it is neither reflected nor refracted? What form of energy is produced in a refrigerator? How much is 5euros in pounds? What is the difference between nuclear and steam and hydroelectric power plants? Does energy appear and disappear? Why does a heating element get hot when current flows? Unlike other forms of energy thermal energy is not easy to what? What is the difference between microfiber and micro denier? A block of wood is at rest on a wooden ramp. When wheels are attached to the block of wood it moves down the ramp. Explain each situation in terms of friction.?

Why is kinetic friction less than static friction?