Answer:
B. -38.2 m/s
Explanation:
Given parameters:
Time of fall = 4s
Unknown:
Final velocity of the rock = ?
Solution:
To solve this problem, we use the expression below;
V = U + gt
V is the final velocity
U is the initial velocity
g is the acceleration due to gravity = 9.8m/s²
t is the time taken
Now, insert the parameters and solve;
V = 0 + (9.8 x 4) = 39.2m/s
