g How many helium-filled balloons would it take to lift a person? Assume the person has a mass of 73 kg and that each helium-filled balloon is spherical with a diameter of 33 cm. Express your answer using two significant figures.

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.

Your answer is 1.5 hope i  

Answer (d) the universe had cooled enough for atoms to combine, protons and neutrons were too far apart to form nuclei;