We make a simple model for shoelaces. Focus on piece AB of the shoelace in the figure. Assume that the friction in hole B is so great that the string is "stuck" there. A force P with an amount of 2 N puts from the foot in the middle of the string so that AB in the tensioned position lifts 1 cm compared to an imaginary straight line between A and B. The straight line is 5 cm. A frictional force Ff resists at A. If the string is wound β = 77 ° along the friction surface in hole A and the coefficient of friction there is µ = 0.4, what will be the force on the knot K from the string piece AK?

B) The round ends of the string at K can be considered as small weights while the string's own weight is negligible.
If you run, can the snow ends pull up the knot? Compare when we accelerate a mass of m hanging in a rope with negligible own mass. The clamping force in such a rope ...?( which one 1-4 is correct?)

1. can increase when the rope is accelerated, even if no weight hangs at the end.

2. can increase when the rope is accelerated, but only if some non-negligible weight hangs at the end.

3. does not increase when the rope is accelerated, because the extra tension is a fictitious force that is not measurable.

4.does not increase when the rope is accelerated, because the clamping force is always zero, as for a lift cable that has been cut.

Answer rating: 100% (QA)

A what will be the force on the knot K from the string piece AK ANSWER The force on the knot K from ... View the full answer