Final answer:
A rock dropped from an 86 m building will hit the ground at approximately 41.04 m/s, calculated using the kinematic equation for free-fall motion, considering constant acceleration due to gravity.
Step-by-step explanation:
The student is asking how fast a rock will be going when it hits the ground if dropped from the roof of an 86-meter-tall building. This question is about the physics of free-fall motion. To determine the final velocity of the rock when it strikes the ground, we can use the equation of motion under constant acceleration due to gravity, which is v = √(2gh), where v is the final velocity, g is the acceleration due to gravity (9.81 m/s²), and h is the height from which the rock is dropped. After plugging in the values, we get:
v = √(2 * 9.81 m/s² * 86 m) = √(1684.92) ≈ 41.04 m/s
Thus, the rock will be going approximately 41.04 m/s when it hits the ground, ignoring air resistance. This concept of free-fall motion is fundamental in kinematics, which is a key component of high school physics.