A guy drove a car from a flat ground on top of a building and laded on the next one that's 100m away several floors down. If the car landed with an angle 30 degrees to x axis, find initial horizontal speed of car?

Initial horizontal velocity = ux (Note this velocity does not affect by gravity so stays the same throughout the jump)

Initial vertical velocity = uy = 0

time to travel horizontal distance, t = (horizontal distance)/(horizontal velocity)

t = 100/ux

This is the same time the car takes to travel vertical distance.

Using one of the equation of motion

vertical landing velocity, vy = uy + gt

vy = 0 + (9.81)(100/ux)

vy = 981/ux

angle of landing = 30°

tan30° = vy/ux

tan30° = (981/ux)/ux

(ux)² = 981/tan30°

ux = 41.22 m/s