If an object is thrown downward at 4.73 m/s and it falls for 6.21 seconds before landing, how fast is it falling the instant before it lands?

Does anyone know how to solve this problem? i really need . i made an attempt but i just cant get it. a metal rod is 25.000 cm long at 25.0 degrees celsius. when heated to 102.0 degrees celsius, it is 25.054 cm long. what is the coefficient of linear expansion for this metal.