question_answer 2)

The position-time (x-t) graphs for two children A and B returning from their school O to their homes P and Q respectively are shown in Fig. 3.82. Choose the correct entries in the brackets below : (a) A /B lives closer to the school than B/A. (b) A/B starts from the school earlier than B/A. (c) A/B walks faster than B/ A. (d) A and B reach home at the (same/different) time. (e) A/ B overtakes B/ A on the road (once/twice.)    Fig. 3.82  

Answer:

(a) As  A lives closer to the school than B. (b) When  for A; while t has some finite value when B starts moving. So A starts from the school earlier than B (c) Speed = Slope of  graph. Slope of  graph > Slope of  graph for B for A.  B walks faster than A (d) Corresponding to the positions P and Q time t is same on time-axis.  A and B reach home at the same time. (e) The  graphs for A and B intersect each other only once. Since B starts from the school afterwards, so B overtakes A on the road once.