Two bullets are fired simultaneously, horizontally and with different speeds from the same place. Which bullet will hit the ground first?

The time of descent t for particle with initial velocity u and angle of projection in projectile motion is given by

Also, the maximum height h of projectile motion is given by

Putting equation (1) in equation (2), we get

Equation (3) above shows that the time taken for descent of projectile is dependent on the maximum height h of the projectile and gravitational acceleration .

Therefore, the two bullets at equal heights, though fired with different speeds, will have equal time of descent. Hence both of them will reach ground simultaneously.