physics

figure 3.1 shows a rectangular concrete slab of weight 18000N. It rests on a brick wall and is the roof of a bus shelter. The concrete slab is 3.0 m wide.
The wall is 2.5 m from the front of the concrete slab and 0.50 m from the back. The cables behind the shelter pull downwards and stop the slab toppling forward.

The concrete slab is of uniform thickness and density. Determine the perpendicular distance between the wall and the centre of mass of the slab?

State the principle of movement?

Calculate the total downward force exerted by the cables on the slab?

  1. 👍 4
  2. 👎 0
  3. 👁 1,122
  1. center of mass of slab is in the center, so it is at1.5 m from the front, or from the wall, 1.0m

    now to balance it,
    Fc=force cables are pulling downward
    Fw=force on the wall downward
    sum forces=0
    18000-Fc+Fw=0
    moments about any point is zero, choose the wall point
    1.0*18000=Fc*0.5
    Fc=36000
    fw=18000

    1. 👍 3
    2. 👎 0
    👨‍🏫
    bobpursley

Respond to this Question

First Name

Your Response

Similar Questions

  1. Physics

    Block B in the figure(Figure 1) rests on a surface for which the static and kinetic coefficients of friction are 0.65 and 0.40, respectively. The ropes are massless.What is the maximum mass of block A for which the system is in

  2. Physics

    One end of a uniform 3.20-m-long rod of weight Fg is supported by a cable at an angle of θ = 37° with the rod. The other end rests against the wall, where it is held by friction as shown in the figure below. The coefficient of

  3. Physics

    A 3.0 kg brick rests on a perfectly smooth ramp inclined at 34 above the horizontal. The brick is kept from sliding down the plane by an ideal spring that is aligned with the surface and attached to a wall above the brick. The

  4. Math

    A concrete patio is 5 2/3 ft wide. It has an area of 36 5/6 square ft. Is the concrete slab long enough to fit a 7-foot picnic table without placing the table along the diagonal of the patio? so far i have 221/6 / 34/6 = 221/34 =

  1. friction

    A 40 kg slab rests on a friction less floor.a 10 kg block rests on top of the slab.the coefficient kinetic friction between the block and the slab is 0.40.a horizontal force of 100N is applied on the 10 kg block.find the resulting

  2. Calculus

    A rectangular garden of area 75 sq ft is to be surrounded on 3 sides by a brick wall costing $12 per foot and on one side by a fence costing $7 per foot. Find the dimensions of the garden that the cost of the materials is

  3. physics

    A tennis ball (m= 0.2 kg) is thrown at a brick wall. It is traveling horizontally at 16 just before hitting the wall and rebounds from the wall at 8 , still traveling horizontally. The ball is in contact with the wall for 0.04 s.

  4. Math--

    A brick layer is hired to build three walls of equal length. He has bricks which are 9 inches, 27 inches, and 21 inches long. He plans to build one wall out of each type of brick. What is the shortest length of wall possible? A)

  1. Physics

    A flat slab of styrofoam, with a density of 32 kg/m^3, floats on a lake. What is the minimum volume the slab must have so that a 42 kg boy can sit on the slab without it sinking?

  2. Physics

    One end of a uniform 2.5-m-long rod of weight 80 N is supported by a cable at an angle of θ = 33° with the rod. The other end rests against the wall, where it is held by friction as shown in the following figure. (Note: There is

  3. statics/physics

    The uniform 10-kg ladder in the figure rests against the smooth wall at B, and the end A rests on the rough horizontal plane for which the coefficient of static friction is 0.3. determine the angle of inclination of the ladder and

  4. math

    You plan to construct a brick wall measuring 14.5 ft. in length, 5.5 ft. high, and 0.5 ft. in width. If a brick measures 6 in. x 4 in. x 2 in., how many bricks will you need? (Remember to round up.)

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