Physics Classical Mechanics

A person of mass m2= 85.0 kg is standing on a rung, one third of the way up a ladder of length d= 4.0 m. The mass of the ladder is m1= 15.0 kg, uniformly distributed. The ladder is initially inclined at an angle θ= 40.0∘ with respect to the horizontal. Assume that there is no friction between the ladder and the wall but that there is friction between the base of the ladder and the floor with a coefficient of static friction μs .

(a) Using the equations of static equilibrium for both forces and torque, find expressions for the normal and horizontal components of the contact force between the ladder and the floor, and the normal force between the ladder and the wall. Consider carefully which point to use for computing the torques. Determine the magnitude of the frictional force (in N) between the base of the ladder and the floor below.


(b) Find the magnitude for the minimum coefficient of friction between the ladder and the floor so that the person and ladder does not slip.

mu_s= 0.426

(c) Find the magnitude Cladder,ground (in N) of the contact force that the floor exerts on the ladder. Remember, the contact force is the vector sum of the normal force and friction.


Find the direction of the contact force that the floor exerts on the ladder. i.e. determine the angle α (in radians) that the contact force makes with the horizontal to indicate the direction.


  1. 👍 0
  2. 👎 0
  3. 👁 298
  1. how did you get part a and b???

    1. 👍 0
    2. 👎 0
  2. @jessica
    b) Find Mu_s first
    Mu_s= (m_p/3 + m_l/2) *cotan (theta)/(m_p+m_l)

    a) Force = Mu_s*g(m_p+m_l)

    1. 👍 0
    2. 👎 0

    1. 👍 0
    2. 👎 0

Respond to this Question

First Name

Your Response

Similar Questions

  1. physics

    Estimate the change in gravitational potential energy when a person with mass 95kg rise from bed to a standing position. Assuming that the center of mass of a person is elevated by approximately Δh=0.50m.

  2. Science

    A 100-kilogram astronaut travels to the moon and steps onto a bathroom scale. The scale reads “16.7 kilograms.” Which statement best describes the reason for this observation? [1 point] A: The scale was designed to use the

  3. physic

    Calculate the pressure exerted on the ground by a79kg person standing on one foot. Assume that the bottom of the person's foot is 13cm wide and 28cm long.

  4. physics

    the problem reads this "A person with mass m1 = 62 kg stands at the left end of a uniform beam with mass m2 = 93 kg and a length L = 3.5 m. Another person with mass m3 = 65 kg stands on the far right end of the beam and holds a

  1. Dudas

    John's mass is 86 kg, and Barbara's is 55 kg. He is standing on the x axis at xj = +9.0 m, while she is standing on the x axis at xb = +2.0 m. They switch positions. How far and in which direction does their center of mass move as

  2. Physics ~please help me~

    1.) Two people of the same mass climb the same flight of stairs. The first person climbs the stairs in 25 s; the second person does so in 35 s. a) Which person does more work?Explain b) Which person produces more power?Explain 2.)

  3. Physics

    1. A person standing motionless between a straight highway and an airport runway. A truck drives by the person at constant speed, while an airplane accelerates down the runway for take off. Of the person, truck, and airplane,

  4. Trigonometry

    Statuary Hal is an elliptical room in the U.S. Capitol. Teh room is also called the Whispering Gallery because a person standing at one focus of the room can hear even a whisper spoken by a person standing at the other focus.

  1. MATH!!!

    Suppose that a person with a reach of 27 inches and a shoulder height of 5 feet is standing upright on a mountainside that makes a 62 degrees angle with the horizontal..Can the person touch the mountain?

  2. physics

    A person of mass 60 kg is standing on a raft of mass 40kg in a lake. The distance of a person from bank is 30m. If a person starts running towards bank with velocity 10m/s then his distance from bank after 1s will be ?? And

  3. PHY

    Standing on level ground, a person casts a shadow 1.41 m long when the Sun is 34.7 degrees above the horizon. How tall is the person? Give your answer in meters.

  4. Math

    A fireman used a ladder with 56 rungs. The rungs are 14 inches apart and 1.5 inches thick. What is the distance from the bottom of the lowest rung to the top of the highest rung? Check if I solved correctly please. I multiplied

You can view more similar questions or ask a new question.