A seesaw consisting of a uniform board of mass M and length L, supports at rest a father and daughter with masses “mf ” and “md”, respective

Question

A seesaw consisting of a uniform board of mass M and length L, supports at rest a father and daughter with masses “mf ” and “md”, respectively.
The support ( called the fulcrum ) is under the centre of gravity of the board , the father is the distance “d” from the center and the daughter is a distance “L/2” from the center.

A) determine the magnitude of the upward force “n” exerted by the support on the board ?

B) determine where the father should sit to balance the system at rest ?​

in progress 0
Thái Dương 5 months 2021-09-02T09:01:40+00:00 1 Answers 0 views 0

Answers ( )

    0
    2021-09-02T09:02:58+00:00

    Answer:

    A) N = (M + mf + md) g

    B) d = md L / (2 mf)

    Explanation:

    Draw a free body diagram.  There are four forces acting on the board.

    Weight force M g pulling down at the center of the board.

    Normal force N pushing up at the center of the board.

    Weight force mf g pulling down a distance d from the center.

    Weight force md g pulling down at the end of the board.

    Sum of forces in the y direction:

    ∑F = ma

    N − M g − mf g − md g = 0

    N = (M + mf + md) g

    Sum of moments about the center of the board:

    ∑τ = Iα

    md (L/2) − mf d = 0

    d = md L / (2 mf)

Leave an answer

Browse

Giải phương trình 1 ẩn: x + 2 - 2(x + 1) = -x . Hỏi x = ? ( )