question_answer 49)

  An object is dropped from rest at a height of 150 m and simultaneously another object is dropped from rest at height 100 m. What is the difference in their heights after 2 s, if both the objects drop with same accelerations? How does the difference in heights vary with time?

Answer:

  For first object given, u = 0 (because object dropped from rest) and time (t) = 2s.      From second equation of motion, the distance covered by first object in 2s is        Height of first object from the ground after 2 s  = 150m -20m = 130m For second object given, u=0 and time (t) = 2 s From second equation of motion, the distance covered by second object in 2 s is Height of second object from the ground after 2s then  = 100m - 20m = 80m Now, difference in the height after 2 = 130 - 80= 50 m The difference in heights of the objects will remain same with time- as both the objects have been dropped from rest and are falling with same acceleration i.e., (acceleration due to gravity).