How Do Forces and Torque Balance in a Ladder Problem with a Firefighter?

  • Thread starter Thread starter vipertongn
  • Start date Start date
  • Tags Tags
    Equilibrium Torque
Click For Summary
SUMMARY

The discussion focuses on calculating the forces acting on a uniform ladder of length L and mass m1, positioned against a frictionless wall, while a firefighter of mass m2 stands at a distance x from the base. The vertical force exerted by the ground is determined by the equation n_g = m1*g + m2*g, where n_g represents the normal force. For the horizontal force, the frictional force must counterbalance the normal force from the wall. Additionally, the coefficient of static friction is derived when the ladder is on the verge of slipping, requiring further analysis of the forces involved.

PREREQUISITES
  • Understanding of static equilibrium conditions (Net Fy = 0, Net Fx = 0, Net T = 0)
  • Familiarity with forces acting on inclined planes
  • Knowledge of torque and moment calculations
  • Basic principles of friction, specifically static friction
NEXT STEPS
  • Study the calculation of moments in static equilibrium problems
  • Learn about the principles of friction, focusing on static friction coefficients
  • Explore the dynamics of forces on inclined surfaces using examples
  • Review the application of Newton's laws in multi-body systems
USEFUL FOR

Students studying physics, particularly those focusing on mechanics, engineers analyzing static structures, and educators teaching concepts of forces and torques in real-world applications.

vipertongn
Messages
97
Reaction score
0

Homework Statement



A uniform ladder of length L and mass m1 rests against a frictionless wall. The ladder makes an angle θ with the horizontal.
(a) Find the horizontal and vertical forces the ground exerts on the base of the ladder when a firefighter of mass m2 is a distance x from the bottom. (Answer using m_1 for m1, m_2 for m2, theta for θ, g for gravity, and L and x as necessary.)
horizontal

(b) If the ladder is just on the verge of slipping when the firefighter is a distance d from the bottom, what is the coefficient of static friction between ladder and ground?


Homework Equations



Net Fy = 0
Net Fx = 0
Net T = 0

The Attempt at a Solution



I tried n_g-m_1*g-m_2*g as the answer for the vertical force because the ladder has a normal force that is exerted in reaction to the two gravitational forces from the ladder itself and the firefighter. I believe that this isn't the correct way to input it.

for the force for horizontal I know its the frictional force minus the normal force from the wall. however I don't know how to input it using hte variables they want.
 
Physics news on Phys.org
vipertongn said:
A uniform ladder of length L and mass m1 rests against a frictionless wall. The ladder makes an angle θ with the horizontal.
(a) Find the horizontal and vertical forces the ground exerts on the base of the ladder when a firefighter of mass m2 is a distance x from the bottom. (Answer using m_1 for m1, m_2 for m2, theta for θ, g for gravity, and L and x as necessary.)
horizontal

(b) If the ladder is just on the verge of slipping when the firefighter is a distance d from the bottom, what is the coefficient of static friction between ladder and ground?

Hi vipertongn! :smile:

Yes, the normal force will be equal and opposite to the other vertical forces.

To find the horizontal forces, take moments about some convenient point. :wink:
 

Similar threads

  • · Replies 20 ·
Replies
20
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 10 ·
Replies
10
Views
3K
  • · Replies 5 ·
Replies
5
Views
3K
Replies
8
Views
7K
Replies
8
Views
1K
Replies
2
Views
4K
  • · Replies 1 ·
Replies
1
Views
1K
  • · Replies 3 ·
Replies
3
Views
5K
Replies
2
Views
2K