Coefficient of static friction of clothes

In summary, a top-loading washing machine with a spin cycle that rotates at 8.5 cycles per second and a spinning drum with a radius of 35 cm will have a linear speed of 19 m/s for the clothes. The magnitude of the normal force acting on a damp pair of jeans with a mass of 2.0 kg by the wall of the drum as it spins is 2083 N. To keep the clothes stuck to the middle of the drum wall, a minimum coefficient of static friction is necessary. The net forces and accelerations in the vertical and horizontal directions should be considered when solving for the minimum coefficient of static friction.
  • #1
tquiva
20
0
Problem:
A top-loading washing machine has a spin cycle that rotates at 8.5 cycles per second. The spinning drub that holds the clothes has a radius of 35 cm.
What is the linear speed of the clothes?
ω = (8.5 cycles/s) / (2pi rad) = 53.4 rad/s
v = ωr = (53.4 rad/s) * (0.35 m ) = 19 m/s

A damp pair of jeans has a mass of 2.0 kg. What is the magnitude of the normal force acting on the jeans by the wall of the drums as it spins?
ΣFy = may
Fn - mg = (mv^2) / (r) = ... = 2083 N

What is the minimum coefficient of static friction necessary so that the clothes can remain stuck to the middle of the drum wall, and not just slide down to the bottom?

I got stuck here on the last question.
I can't seem to figure out what a is in the x direction. My guess is 0, so the static friction is 0?
But that doesn't sound right. Could someone help me please?
 
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  • #2
tquiva said:
Problem:
A top-loading washing machine has a spin cycle that rotates at 8.5 cycles per second. The spinning drub that holds the clothes has a radius of 35 cm.
What is the linear speed of the clothes?
ω = (8.5 cycles/s) / (2pi rad) = 53.4 rad/s
v = ωr = (53.4 rad/s) * (0.35 m ) = 19 m/s
yes, looks good!
A damp pair of jeans has a mass of 2.0 kg. What is the magnitude of the normal force acting on the jeans by the wall of the drums as it spins?
ΣFy = may
Fn - mg = (mv^2) / (r) = ... = 2083 N
not good...
What is the minimum coefficient of static friction necessary so that the clothes can remain stuck to the middle of the drum wall, and not just slide down to the bottom?

I got stuck here on the last question.
I can't seem to figure out what a is in the x direction. My guess is 0, so the static friction is 0?
But that doesn't sound right. Could someone help me please?

You seem to be confusing your x and y directions. For the second part, what is the direction of the centipetal acceleration? What is the net force in that direction (normal forces act pependicular to the objects on which they act)?
For part 3, what is the net force in the vertical direction? What is the acceleration in the vertical direction (friction forces beween two contact surfaces act parallel to the plane of the contact surfaces)?
 

What is the coefficient of static friction?

The coefficient of static friction is a measure of the force required to overcome the static friction between two surfaces in contact with each other. It is represented by the symbol μs and is a dimensionless quantity.

How is the coefficient of static friction of clothes determined?

The coefficient of static friction of clothes can be determined experimentally by measuring the force required to move a clothed surface, such as a piece of fabric over a flat surface, and dividing it by the weight of the object. It can also be calculated by using the formula μs = F/N, where F is the force required to move the object and N is the normal force.

What factors affect the coefficient of static friction of clothes?

The coefficient of static friction of clothes can be affected by several factors, including the material of the clothing and the surface it is in contact with, the amount of force applied, and the presence of any lubricants or other substances on the surfaces.

Why is the coefficient of static friction important for clothing?

The coefficient of static friction is important for clothing because it affects how easily the clothing can move or slide against other surfaces. This can impact the comfort and functionality of clothing, as well as its durability and ability to resist wear and tear.

How does the coefficient of static friction of clothes differ from the coefficient of kinetic friction?

The coefficient of static friction represents the force needed to overcome the initial resistance between two surfaces, while the coefficient of kinetic friction represents the force needed to maintain motion between the surfaces. In other words, the coefficient of static friction is typically higher than the coefficient of kinetic friction.

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