فيزياء: أي استفسار أول سؤال

[مالي بالدنيا سواك]

الاستاذه طلبت حل هذي الاسئله ياليت تساعدوني..
A projectile is fired horizontally from a gun that is 45.0 m above flat ground,emerging from the gun with a speed of 250 m\s. a)How long does the projectile remain in the air?
b)At what horizontal distance from the firing point does it strike the ground?
c)What is the magnitude of the vertical component of its velocity as it strikes the ground?
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An Earth satellite moves in a circular orbit 640 km above Earth`s surface with a period of 98.0 min.What are the a)speed and b)magnitude of the centripetal acceleration of the satellite?