Question

a ball thrown vertically upwards from level ground is observed twice, at a height H above the ground, within a time interval t.The initial velocity of the ball was
a. \[\sqrt{8gH+g ^{2}t ^{2}}\]
b. \[\sqrt{8gH+\left( gT/2 \right)^{2}}\]
c.\[1/2\sqrt{8gH+g ^{2}t ^{2}}\]
d. \[\sqrt{8gH+4g ^{2}t ^{2}}\]