Part A Suppose that you toss a rock upward so that it rises and then falls back to the earth. If the acceleration due to gravity is 9.8 m/sec , what is the rock's acceleration at the instant that it reaches the top of its trajectory (where its velocity is momentarily zero)? Assume that air resistance is negligible. O The acceleration of the rock is zero. O The rock has a downward acceleration of 19.6 m/s2. The rock has a downward acceleration of 9.8 m/s2 O The rock has an upward acceleration of 9.8 m/s2 O The rock has an upward acceleration of 19.6 m/s2. Submit Request Answer Provide Feedback Next >