فيزياء: أي استفسار أول سؤال

[CDTOE]

أعطانا الدكتور ورقة فيها 7 مسائل في السقوط الحر , حليت حتى الآن 3 منها , ولكن ابغى اتاكد من الجواب منك :

1 - a ball thrown vertically from the ground level to rise to a maximum height of 50m . What is the initial velocity of the ball ?

2 - a ball thrown vertically upward is caught by the thrower after 20 sec . What is the initial velocity of the ball ?

3 - A stone is dropped from a building at height of 25 m . What's its height when the speed of the stone is 12.6 m/s ?

شكرا مقدما .