Physics
posted by Sophie .
I push a stack of six books (each weighting 4 kg) horizontally across a table to the right with a kinetic coefficient of friction uk = 0.5. I apply a force of 120 N.
a) What is the acceleration of the books?
b) what is the force of the rightmost book on its neighbor?
Next, I stack the books vertically and push them horizontally across a table to the right by applying a force only to the bottom book.. The kinetic coefficient of friction of the books with the table is uk=0.5 and the static coefficient of friction between the books is us=0.3.
c) What is the maximum force I can apply to the bottom book to move the books as a single unit, before books starts to fall off the stack?
I solved for a) and b) already. For a) I got 5 m/s^2 and for b) I got 40N.
But I am stuck on part c.
I don't really understand how to start because I know that the normal force would be constantly changing, but I don't know how does the kinetic friction and static friction plays in for finding the maximum force that I can apply to the books.
Can someone please explain to me how to finish the problem? Thank you.

How fast can the stack accelerate without the books above the first one slipping?
weight down on bottom book = 5 * 4 kg * g
maximum static friction force between top 5 and bottom book = 5 * 4 * g * 0.3
so max force = mass of top 5 * a
5*4*g*.3 = 5*4 * a
so
a = .3 g
that gives us the maximum acceleration before we get a slip
now what force gave that acceleration?
F = m a
F = 6 * 4 * a
F = 24 * .3 g
if g = 9.81 m/s^2
F = 70.6 Newtons 
shouldn't you take into consideration the kinetic friction, the less force you need according to this method you would need more force if you have 100 books.
Respond to this Question
Similar Questions

Physics Help2I!!!
There are six books in a stack, and each book weighs 5N. The coefficient of friction between the books is 0.2. With what horizontal force must one push to start sliding the top five books off the bottom one? 
physics
please help There are six books in a stack, and each book weighs 5 N. The coefficient of static friction between the books is 0.2. With what horizontal force must one push to start sliding the top five books off the bottom one? 
Physics
There are six books in a stack, and each book weighs 5 N. The coefficient of static friction between the books is 0.2. With what horizontal force must one push to start sliding the top 5 books off the bottom one. my answer is 3N but … 
physics
A popular pastime is to see who can push an object closest to the edge of a table without its going over. You push a 130 g object and release it 2.00 m from the table edge. Unfortunately, you push a little too hard. The object slides … 
Physics 1
There are six books in a stack, and each book weighs 5 N. The coefficient of static friction between the books is 0.2. With what horizontal force must one push to start sliding the top five books off the bottom one? 
Physics
I have 3 different questions. 1) Calculate the coefficient of kinetic friction if it takes a force of 64 Newtons to keep a 54 kilogram box of books sliding across any icy surface at a uniform speed. 2) A car weighing 14,000 Newtons … 
physics
box full of books rests on a wooden floor. The normal force the floor exerts on the box is 235 N. a) You push horizontally on the box with a force of 121 N, but it refuses to budge. What can you say about the coefficient of static … 
physics MC QUESTIONS
1. You push a block up a ramp with friction. The block is moving at constant speed ? 
Mechanics
A man attempts to support a stack of books horizontally by applying a compressive force of F = 120 N to the ends of the stack with his hands. If each book has a mass of 0.95 kg, determine the greatest number of books that can be supported … 
Physics
An 103 Newtons box of oranges is being pushed across a horizontal floor. As it moves, it is slowing at an acceleration of 0.9m/s2. The push force has a horizontal component of 20N and a vertical component of 25N downward. Calculate …