Would a car tow rope withhold an adult person?

Question

I am not exactly sure how the physics work here. If we take a car tow rope, which is manufactured for towing a 3500 kg car and we actually start towing such a car on this rope, what force do we really apply to the rope?

Could the same rope safely withhold an adult person (100 kg) hanging on it?

Answer 1

It depends on rolling resistance of wheels, friction resistance in bearings, elevation and acceleration of pulled car.

$ F=F_r+F_f+F_e+F_a $

where:

• $F$ is total force,
• $F_r=\frac{N_fb}{r}$ is rolling resistance, $b$ is rolling resistance coefficient, $r$ is radius of the wheel and $N_f$ is normal force,
• $F_f=\mu N_f$ is friction force and $\mu$ is friction coefficient,
• $F_e=mg*\sin\alpha$ is part of gravitation force, $\alpha$ is angle of slope, $m$ is mass,

• $F_a=ma$ is acceleration force, $a$ is acceleration.

  So it depends on bearings condition, tires and surface conditions, and many other variables...

If you want to know whether 3.5 ton rope can lift 100 kg ask sports specialist, especially climbers, whether 100 kg safe rope can pull 3.5 ton car.

Answer 2

Actually there's three kinds of ropes one might hang an adult human from.

A rock climbing rope is designed with a great deal of stretch. Thus when someone falls the rope decelerates them slowly, thereby lowering the peak force applied to the rope. To find these google "dynamic climbing rope".

Ropes used in rescue are not intended to catch falls. Accordingly they are designed with much less stretch. This makes for a more comfortable ride. To find these, google "low stretch rescue rope" or "static rescue rope".

Ropes used for execution are the third type. With these, safety is not a great concern.