classsical mechanics question:
while climbing a chute, what force must you apply to against the walls to support your weight? Coefficient of friction b/w wall-boots=0.56 and wall-gloves=0.39. assume you exert equal forces with hands and feet.

Question

classsical mechanics question:
while climbing a chute, what force must you apply to against the walls to support your weight? Coefficient of friction b/w wall-boots=0.56 and wall-gloves=0.39. assume you exert equal forces with hands and feet.

anonymous · Answer

assume the climber climbs the wall like this:|dw:1415400340948:dw|

noelgreco · Answer

The answer varies depending on the angle at which the hands and feet meet the walls of the chute.

anonymous · Answer

it says optimal angle so i assume its 45

anonymous · Answer

does it depend on the mass?

noelgreco · Answer

Well, the angle of the legs and arms would differ (for most people).  If I were climbing, I'd want a lot smaller angle than 45.

I hate to judge, but it's not a very good question.

anonymous · Answer

i know right. i don't know why they gave this question in my assignment

noelgreco · Answer

You could answer by stating that you assumed the optimal angle of the arms to be 45 and the legs to be 30.  That's not reasonable, but the angles have nice, simple trigonometric  values.

anonymous · Answer

but how do i go about solving it without the mass of the person?

anonymous · Answer

Heres the question. straight from the textbook:
Note:  The magnitude of the force exerted by each of the hands and legs is the same. Assume the climber chooses the optimal angle at which the hands and legs press against the walls.

noelgreco · Answer

They aren't looking for the force in Newtons.  The answer will include "m" for the mass of the climber.

noelgreco · Answer

I re-thought this problem while trying to get back to sleep last night.

There are no angles and no trig involved.
|dw:1415486094524:dw|
The forces against the walls are all the same (F), and the sum of the forces opposing mg is simply 2(.39F + .56F), and this has to be equal to mg for the person not to fall.

Solve for F in terms of m and g.

anonymous · Answer

thats what i did but my assignment requires a solid answer. Not in terms of M, which is impossible as the force would change as per the mass of the person......unless theres a way to eliminate M by taking moments about a point....