Two balls are projected simultaneously with the same speed from the top of a tower, one vertically upward and the other vertically downward. They reach the ground in 9 s and 4 s respectively. The height of the tower is (g=10 m s⁻²):
Options

Question

Two balls are projected simultaneously with the same speed from the top of a tower, one vertically upward and the other vertically downward. They reach the ground in 9 s and 4 s respectively. The height of the tower is (g=10 m s⁻²):

Options

G1 Physics · Accepted Answer

For equal-speed launches upward and downward from the same tower, the product of flight times is T₁T₂=2H/g. Therefore H=(g/2)(9)(4)=180 m. Hence option B.