Sounds like a homework question so I won't answer it but give some tips. You know the initial velocity of the marble. It is 0 m/s. You know the height of the building. 400 m. You have a time. 6.22 s You know or can get the acceleration due to gravity. It is -9.8 m/s^2 (negative because of coordinate conventions - up is positive hence the height is +400 m) In the first part v (the velocity at time t) is unknown. It is sometimes useful to extract the data in this manner or even better (I've left the units out but you should include them as well): u = 0 s= 400 t = 6.22 a= - 9.8 v = ? Now you should know the equations of motion. If not look them up. Find one that uses the above and solve for v. Using the equations of motion again for part two you can then calculate v when 400m has been travelled i.e. when it hits the ground. There are a number of ways to do this e.g. find the time taken to fall the required distance and then work out the velocity at this time, similar to how you did part one. The key is to find an equation or equations that can take the data you have and give you the value of something unknown. Write the equations out and you will quickly see which ones are applicable as they match up with the data you have. That's why writing the data out in a list is useful. You can 'cross them off' if need be. Then just solve them.

Not in the right mind to do maths/physics, but I would suspect the weight of the marble would need to come into it somewhere along the line...

32 ft/second squared.