Solve Homogeneous Ladder Problem - Max Height Reachable

  • Thread starter madahmad1
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In summary: The normal force of the wall is the sum of these two forces, so it's bigger when the man is higher up on the ladder.
  • #1
madahmad1
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Homework Statement



A homogeneous ladder having a length of 6m and a mass of 35kg is positioned. The lower base of the ladder has an angle of 60 degrees with the ground and the coefficient of friction between former and the latter is 0.3. Define the maximum height a human can reach, which has a weight if 70kg.

Homework Equations



What equation is applied here?


The Attempt at a Solution



I can not find an equation that can apply to this question.
 
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  • #2
You need to find the force friction of the ladder (with the human) with respect to the ground. This is given by uk*N. Where uk is the coefficient of friction and N is the normal force.
 
  • #3
In all these kinds of Statics problems, the method is to draw a freebody diagram, then equate the sums of the horizontal and vertical components of forces individually to zero, and take moment of all the forces about a suitable point and equate it to zero.

Suppose the man climbs up to a vertical height h on the ladder, when the force of static friction is maximum. Start with drawing a freebody diagram and label the forces.
 
  • #4
i don't understand how the weight of the man affects the frictional force as he moves up. the normal is equal to the weight of (ladder + man). both act in opposite directions, and as the man climbs up, the sum of weight remains the same.

though i do realize that this makes no sense. i can't understand why.
 
  • #5
You have to consider the normal reaction of the wall, too.
 
  • #6
then is it correct to say that the force against which friction acts is equal to the normal force of wall on ladder? it is when this normal force is greater than the frictional force that the ladder slides down... i got it right??

now what i can't understand is how we get the normal force of wall on ladder? does it increase as the man climbs up?
 
  • #7
Right. Yes, it does increase as the man climbs up.

If you look at the horizontal forces in the problem, there are only two -- the normal reaction at the point of contact at the wall and the friction at the point of contact at the ground. These two must be equal and opposite as long as the ladder doesn't slip.
 

1. How do you solve the homogeneous ladder problem?

To solve the homogeneous ladder problem, you need to use the Pythagorean theorem. First, determine the length of the ladder and the height of the wall it is leaning against. Then, use the Pythagorean theorem to calculate the distance from the base of the wall to the top of the ladder. This will give you the maximum height reachable by the ladder.

2. What is the Pythagorean theorem?

The Pythagorean theorem is a mathematical formula that states that in a right triangle, the square of the length of the hypotenuse (the side opposite the right angle) is equal to the sum of the squares of the lengths of the other two sides. It can be written as a^2 + b^2 = c^2, where c is the length of the hypotenuse and a and b are the lengths of the other two sides.

3. What is a homogeneous ladder?

A homogeneous ladder is a ladder that has the same material and thickness throughout its length. This means that the ladder is uniform and does not vary in weight or strength at different points.

4. Can the homogeneous ladder problem be solved using other methods besides the Pythagorean theorem?

Yes, there are other methods that can be used to solve the homogeneous ladder problem, such as using trigonometric functions or similar triangles. However, the Pythagorean theorem is the most commonly used method and is often the simplest and most efficient way to solve the problem.

5. What are some real-life applications of the homogeneous ladder problem?

The homogeneous ladder problem has many practical applications, such as determining the maximum height that can be reached by a ladder when painting a wall, installing shelves, or fixing a roof. It can also be used in engineering and construction to ensure the stability and safety of ladders and other structures.

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