Question

Serena drops a 5-kg book down the stairwell. What is the book's final velocity vf after it falls

freely for 4 seconds

Answer 1

39.2m/s

Step-by-step explanation:

Given parameters:

Mass of book = 5kg

Time taken for fall = 4s

Unknown:

Final velocity of the book = ?

Solution:

Serena dropped the book from rest therefore, the initial velocity of the book is 0.

Let us find the appropriate motion equation to solve this problem;

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

Insert the given parameters and solve;

V = 0 + 9.8 x 4 = 39.2m/s