Gravity, Friction, and Rope Climbing.

Most recent answer: 09/28/2012

Q:
hi um what does gravity and friction have to do with climbing a rope
- amy (age 9)
ny
A:
Hello Amy,
Gravity is responsible for the downward force on your body.  Your weight is directly proportional to your mass, the mass of the earth, and Newton's gravitational constant. So the more you weigh, the more force you need to climb a rope.
Friction is a force that resists motion between two sliding bodies.  For example, ice has a very small value of the friction coefficient so it is hard to stop a car on an icy road.   If there were no friction between your hands and the rope, it would be like trying to climb up an icicle or a wet noodle.  In technical terms the force of friction is given by
Ffriction = Fnormal x Cfriction  ,
where Ffriction is the frictional force,  Fnormal is the force you apply to the rope in order to hang on,  and Cfriction is the coefficient of friction which varies for material to material.  Cfriction  is large for a rough surface and very small for an icy surface.   So as long as Ffriction  is larger than the force of gravity you can climb, otherwise you stay on the floor.

LeeH

(published on 09/28/2012)