How Friction Helps Scissors Cut Wires
Why does a wire slip to the ends of scissors before being cut?
a) The wire is attracted to the scissors
b) The scissors are magnetized
c) Friction prevents the initial slipping of the wire
d) The force of gravity is too weak to affect the wire
How can we determine the coefficient of friction of the wire on the blade of the scissors?
Answer:
The wire slips to the end of the scissors and is only cut when the opening angle decreases because of friction; the coefficient of friction can be found by examining when the slipping stops. Gravity is ignored, and it is not necessary for the scissors or wire to be magnetized for this effect.
Explanation: When a wire slips to the ends of the scissors and only cuts when the opening angle decreases, it indicates that friction is the force preventing the wire from being cut initially. As the scissors close, the angle decreases, increasing the normal force between the wire and the blades. This increase in normal force enhances the frictional force to a point where it is large enough to prevent the wire from slipping and allowing the scissors to cut the wire.
The coefficient of friction of the wire on the blade can be determined by examining the point at which the wire stops slipping and starts being cut. This is related to the angle, the force applied by the scissors, and the properties of the wire's material. From the provided scenarios, it is clear that the friction is the cause (c) for the wire's initial slipping and eventual cutting.