You are shadowing a nurse in the emergency room of a local hospital. An orderly wheels in a patient who has..?

Question

You are shadowing a nurse in the emergency room of a local hospital. An orderly wheels in a patient who has been in a very serious accident and has had severe bleeding. The nurse quickly explains to you that in a case like this, the patient's bed will be tilted with the head downward to make sure the brain gets enough blood. She tells you that, for most patients, the largest angle that the bed can be tilted without the patient beginning to slide off is 32.0 degrees from the horizontal.

a. on what factor does this angle of tilting depend?
b. find the coefficient of static friction between a typical patient and the bed's sheets.

This problem is giving me trouble.
Please help me to understand it.

Please mark each part to the question to avoid confusion.

Answer 1

Ok let me start by sayng that I dont know enough to give an informed answer on b.
a. The tilting factor would depend on the force of friction between the patient and the sheet. Some materials would promote sliding more quickly than others (silk for example), other would inhibit sliding. Also to be considered is th weight of the patient...heavier will slide quicker coz of more force.

Answer 2

well I wont do your homework for you but here is a clue
determine the force of the patient sliding.
you know the angle, think of sin cos tan.
now which one would you use in this case?
draw out a diagram, label what you know and what you want
now which equation will give you the force of the patient when he starts sliding?
hint : it will be an equation.

a) what does it depend on? well how about the type of clothes the patient wears, obviously shiny plastic dance clothes would slide more than say a velcro suit. what about the bed sheets, silk sheets would be more slipery than say flannel.

b) if you know the force the patient will exert when he starts to slide you know the coefficient of static will exactly equal this force at 32 degrees. Any more and the patient slides, so it overcomes friction, and any less and friction is far more than the force.

Answer 3

The equilibrim angle is where the component of gravity parallel to the sheets equals the static friction. Draw a little sketch to see the force balance and the angles involved.

Answer 4

Regis...... i'd like to phone a friend.