A body falling under gravity covers two points A and B separated by 80 m in 2 s. The distance of upper point A from the starting point is m (use g=10 ms-2).
45
Let the speed at A be vA (start O from rest, OA = h).
A B: s=vAt+ 12gt2
80=2vA+ 12 10 22 vA=30 m/s
O A (from rest): vA2=2gh
h= 3022 10=45 m
Answer: 45
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