A 550N physics students stand on a bathroom scale in an 850 kg(including the student) elevator that is supported by a cable. As the elevator starts moving, the scale reads 450N. (a) Find the acceleration of the elevator(magnitude and direction). (b) What is the acceleration if the scale reads 670N? (c) if the scale reads zero, should the student worry? Explain (d) what is the tension in the cable in parts (a) and (c)?