Answer:
b. 4.2 m/s²
Step-by-step explanation:
The final velocity of the rock is zero. Therefore, the change in velocity is:
Δv = vf - vi = 0 - 5.0 = -5.0 m/s
The distance covered by the rock is 3.0 m. Therefore, the average acceleration is:
a = Δv / Δt
We do not have the value of time, so we can't calculate the acceleration directly. However, we can use the equation of motion that relates the initial velocity, final velocity, acceleration, and distance covered:
d = (vf² - vi²) / (2a)
Substituting the given values:
3.0 = (0² - 5.0²) / (2a)
Solving for acceleration:
a = -25 / (2 x 3.0) = -4.2 m/s²
The magnitude of the average acceleration is 4.2 m/s².
Therefore, the answer is (b) 4.2 m/s².