Question : A ball kicked vertically up attains a height of 19.6m and returns to the point of throw. If the ball is in air for four second, then the value of acceleration due to gravity is
(A) 4.9ms^{-2}
(B) 9.8ms^{-2}
(C) 10ms^{-2}
(D) 2 × 4.9ms^{-2}
Answer : option (B)
Solution :
