Answer
given,
height of window = 4 m
time taken to travel = 1 s
acceleration due to gravity = 9.8 m/s²



u = -0.905 m/s
initial velocity of ledge v = 0
now,
v² = u² + 2 a s
(-0.905)² = 0 + 2 × 9.8 ×s
s = 0.042 m
Answer: I think the answer C
Explanation:
We have that for the Question "A 2kg book is held against a vertical wall. The <em>coefficient </em>of friction is 0.45. What is the minimum force that must be applied on the <em>book</em>, perpendicular to the wall, to prevent the book from slipping down the wal" it can be said that the minimum force that must be applied on the <em>book is</em>
From the question we are told
A 2kg book is held against a vertical wall. The <em>coefficient </em>of friction is 0.45. What is the minimum force that must be applied on the <em>book</em>, perpendicular to the wall, to prevent the book from slipping down the wal
Generally the equation for the Force is mathematically given as

F=44N
Therefore
the minimum force that must be applied on the <em>book is</em>
F=44N
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