6. A uniform ladder 10.0 m long is leaning against a frictionless wall at an angle of 60.0° above the horizontal. The weight of the ladder is 50.0 N. A 150.0 N boy climbs 4.00 m up the ladder. What is the magnitude of the frictional force exerted on the ladder by the floor?

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**Problem Statement:**

A uniform ladder 10.0 m long is leaning against a frictionless wall at an angle of \(60.0^\circ\) above the horizontal. The weight of the ladder is 50.0 N. A 150.0 N boy climbs 4.00 m up the ladder. What is the magnitude of the frictional force exerted on the ladder by the floor?

**Solution:**

1. **Determine Forces Acting on the Ladder:**
   - The weight of the ladder, \( W_L = 50.0 \text{ N} \)
   - The weight of the boy, \( W_B = 150.0 \text{ N} \)
   - The perpendicular distance to the ladder's center of gravity from the wall (half the ladder's length due to uniformity) is \( \frac{10.0 \, \text{m}}{2} \cos(60^\circ) = 5.0 \, \text{m} \cos(60^\circ) \).
   - The perpendicular distance to the boy is \( 4.0 \, \text{m} \cos(60^\circ) \).

2. **Assume Equilibrium Conditions:**
   - Sum of horizontal forces equals zero.
   - Sum of vertical forces equals zero.
   - Sum of moments about the bottom of the ladder equals zero (to find frictional force).

3. **Vertical Forces:**
   - \( F_N - W_L - W_B = 0 \)
   - \( F_N = W_L + W_B \)
   - \( F_N = 50.0 + 150.0 = 200.0 \text{ N} \) (Normal force from the floor).

4. **Horizontal Forces:**
   - \( F_f = F_W \) and \( F_W = F_N \tan(60^\circ) \)
   - \( F_f \) = frictional force from the floor
   - \( F_W \) = force from the wall

5. **Moments About the Bottom of the Ladder:**
   - \( W_L \times 5.0 \cos(60^\circ) + W_B \times 4.0 \cos(60^\circ) = F_W \times 10.0 \sin(60^\circ) \)
   - \( 50.0 \times
Transcribed Image Text:**Problem Statement:** A uniform ladder 10.0 m long is leaning against a frictionless wall at an angle of \(60.0^\circ\) above the horizontal. The weight of the ladder is 50.0 N. A 150.0 N boy climbs 4.00 m up the ladder. What is the magnitude of the frictional force exerted on the ladder by the floor? **Solution:** 1. **Determine Forces Acting on the Ladder:** - The weight of the ladder, \( W_L = 50.0 \text{ N} \) - The weight of the boy, \( W_B = 150.0 \text{ N} \) - The perpendicular distance to the ladder's center of gravity from the wall (half the ladder's length due to uniformity) is \( \frac{10.0 \, \text{m}}{2} \cos(60^\circ) = 5.0 \, \text{m} \cos(60^\circ) \). - The perpendicular distance to the boy is \( 4.0 \, \text{m} \cos(60^\circ) \). 2. **Assume Equilibrium Conditions:** - Sum of horizontal forces equals zero. - Sum of vertical forces equals zero. - Sum of moments about the bottom of the ladder equals zero (to find frictional force). 3. **Vertical Forces:** - \( F_N - W_L - W_B = 0 \) - \( F_N = W_L + W_B \) - \( F_N = 50.0 + 150.0 = 200.0 \text{ N} \) (Normal force from the floor). 4. **Horizontal Forces:** - \( F_f = F_W \) and \( F_W = F_N \tan(60^\circ) \) - \( F_f \) = frictional force from the floor - \( F_W \) = force from the wall 5. **Moments About the Bottom of the Ladder:** - \( W_L \times 5.0 \cos(60^\circ) + W_B \times 4.0 \cos(60^\circ) = F_W \times 10.0 \sin(60^\circ) \) - \( 50.0 \times
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