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A uniform ladder rests against a frictionless wall at an angle of theta = 46.0° with respect to the ground. if the weight of the ladder is wl = 300 n, the length is l = 8.5 m, and the coefficient of static friction between the ladder and the ground is s = 0.75, determine the distance a man with a weight of wm = 800 n can climb along the ladder before the ladder begins to slip.

User Dave Moore
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1 Answer

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Final answer:

The man cannot climb along the ladder because the coefficient of static friction is greater than 1.

Step-by-step explanation:

When a ladder rests against a wall, there are four forces acting on it: the normal reaction force from the floor, the static friction force between the ladder and the floor, the weight of the ladder, and the normal reaction force from the wall. In this case, we need to find the distance a man with a weight of 800 N can climb along the ladder before it begins to slip.

Let's start by resolving the forces in the vertical and horizontal directions. In the vertical direction, we have the normal reaction force from the floor (N) and the weight of the ladder (Wl) acting downwards. In the horizontal direction, we have the static friction force (Fs) and the normal reaction force from the wall (Fw).

Using trigonometry, we can relate the forces and angles:

  • Vertical direction: N - Wl = 0
  • Horizontal direction: Fs - Fw = 0

From the vertical equilibrium equation, we can find the normal reaction force from the floor:

N = Wl = 300 N

Since the ladder is in static equilibrium, the static friction force will be equal to the force from the wall:

Fs = Fw

Substituting Fs = us * N and Fw = wm * g, where us is the coefficient of static friction between the ladder and the ground, and g is the acceleration due to gravity:

us * N = wm * g

us * 300 N = 800 N * 9.8 m/s^2

us = (800 N * 9.8 m/s^2) / 300 N ≈ 26.13

Since the coefficient of static friction cannot be greater than 1, the ladder will slip before the man can climb any distance along it. Therefore, the man cannot climb along the ladder.

User Entela
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