An object thrown directly upward is at a height of s=-16t +961 + 288 feet after t seconds. (a) What is its initial velocity? (b) When does it reach its maximum height? (c) What is its maximum height? (d) When does it hit the ground? (e) With what speed does it hit the ground? (a) The object's initial velocity is ft/sec. (b) The object reaches its maximum height at time t= (Round to the nearest tenth as needed.) sec (c) The object's maximum height is s = ft (Round to the nearest tenth as needed.)