question_answer 30)

                    A lift is coming from 8th floor and is just about to reach 4th floor. Taking ground floor as origin and positive direction upwords for all quantities, which one of the following is correct?                 (a) \[x<0,\,\,\upsilon ~<0,\text{ }a>0\]                 (b) \[x>0,\,\,\upsilon ~<0,\text{ }a<0\]                 (c) \[x>0,\,\,\upsilon ~<0,\text{ }a>0\]                 (d) \[x>0,\,\,\upsilon ~>0,\text{ }a<0\]                

Answer:

  (a) Distance travelled and velocity are negative and acceleration is positive.