Question

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/sec2, 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.

Answer 1

-- The acceleration of the rock is zero.
--The rock has an upward acceleration of 19.6 m/s2.
--The rock has a downward acceleration of 19.6 m/s2.
--The rock has a downward acceleration of 9.8 m/s2.
--The rock has an upward acceleration of 9.8 m/s2.

Answer 2

I thought we covered this yesterday? The rock has a downward acceleration of 9.8 m/s^2

Answer 3

oh right I put up the wrong question thanks for catching that =)