Atropical storm turns into a hurricane when wind speeds reach?

A tropical storm turns into a hurricane when wind speeds reach more than 33 knots. It happens when the tropical depression strengthens and then the speed of the wind starts increasing and reaches a stage when it is called a hurricane. Right type of condition can create a powerful hurricane, but when the right conditions are not there, then the storm fizzles out. 

Is a  vector quantity  that refers to "the rate at which an object changes its position." imagine a person moving rapidly - one step forward and one step back - always returning to the original starting position. while this might result in a frenzy of activity, it would result in a zero velocity. because the person always returns to the original position, the motion would never result in a change in position. since velocity is defined as the rate at which the position changes, this motion results in zero velocity. if a person in motion wishes to maximize their velocity, then that person must make every effort to maximize the amount that they are displaced from their original position. every step must go into moving that person further from where he or she started. for certain, the person should never change directions and begin to return to the starting position.