Kinetic friction incline problem

In summary, To determine the tension in the rope while Mildred is pulling a sled loaded with beer, it is necessary to consider the forces acting on the sled in both the x and y directions. The coefficient of kinetic friction, mass of the sled and beer, and the angle at which the rope is inclined are all factors that need to be taken into account. By using the appropriate equations and applying basic algebra, the tension in the rope is found to be approximately 91N.
  • #1
Nirupt
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Homework Statement


Mildred pulls a sled loaded with beer along a horizontal surface at constant velocity, as Bubba told her he needed it for he and his buddies to watch the football game. If the sled and beer in it has mass = 75 kg, the coefficient of kinetic friction μk between the runners and the snow is 0.10, and she is pulling a rope inclined at an angle of 42 degrees, what is the magnitude of the tension in the rope?

Homework Equations





The Attempt at a Solution



X direction:

μκ = .1

Fκ = .1*Fn


ƩFnetχ = Fτ*cos(42) - μκ*Fn = 0


ƩFnety = Fn + Fτ*sin(42) - mg = 0
Fn = -Fτ*sin(42) + mg

so I plug this for Fn

Fτ*cos(42) - μκ*(-Fτ*sin(42) + mg) = 0

Fτ*cos(42) + μκ*Fτ*sin(42) - μκ*mg = 0
Fτ = μκ*mg/cos(42) + μκsin(42)
Fτ = .1*735/(cos(42) + .1*sin(42))
Fτ = 73.5/.0669
Fτ = 90.7504
F ≈91N

Just checking to make sure this is correct. I feel like I messed up my algebra with Fτ.. I mean.. would it be 2Fτ or Just Fτ like I have it. I feel like basic algebra can be kind of overwhelming at time.
 
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  • #2
Your working looks correct until you evaluated (cos(42) + .1*sin(42)). cos(42deg) > cos(45deg) = sqrt(2)/2 > .7.
 

FAQ: Kinetic friction incline problem

1. What is kinetic friction?

Kinetic friction is the force that opposes the motion of an object as it slides across a surface. It is caused by the microscopic irregularities on the surface of the object and the surface it is sliding on.

2. How is kinetic friction different from static friction?

Static friction is the force that prevents an object from moving when a force is applied to it, while kinetic friction is the force that acts on an object as it is already in motion. Static friction is usually greater than kinetic friction.

3. How does the angle of an incline affect kinetic friction?

The angle of an incline can affect the magnitude of kinetic friction. As the angle increases, the component of weight parallel to the incline increases, resulting in a greater normal force and thus a greater kinetic friction force.

4. What factors affect the magnitude of kinetic friction?

The magnitude of kinetic friction is affected by the type of surfaces in contact, the normal force between the two surfaces, and the roughness of the surfaces. It also depends on the weight and velocity of the object.

5. How is kinetic friction calculated in an incline problem?

To calculate kinetic friction in an incline problem, first determine the normal force by multiplying the weight of the object by the cosine of the angle of the incline. Then, multiply the normal force by the coefficient of kinetic friction to find the magnitude of the frictional force acting on the object.

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