Question

a rock is thrown straight up and reaches a maximum height. air friction is negligible. which of the following describes the motion at the maximum height? multiple choice the velocity is zero and the acceleration is zero. the velocity is maximum and the acceleration is zero. the acceleration is not changing (a_y = -9.80 m/s²) and the velocity is zero. the acceleration is increasing and the velocity is zero.

Explanation:

When a rock is thrown straight up, at maximum height, its velocity is zero (momentarily stops). Acceleration due to gravity ($a_y = -9.80\ m/s^2$) is constant (no air friction), so acceleration doesn't change. Other options are wrong: velocity isn't max (it's zero), acceleration isn't zero or increasing.

Answer:

The acceleration is not changing ($a_y = -9.80\ m/s^2$) and the velocity is zero.