A diver of weight 650 N stands at the end of a diving board

A diver of weight 650 N stands at the end of a diving board( L = 5 m) and negligible mass. The board is fixed to two pedestals separated by d = 1.5 m.

(a) What are the magnitude and direction of the force on the board from the left pedestal?

(b) What are the magnitude and direction of the force on the board from the right pedestal?

(c) Which pedestal is being stretched and which is being compressed? Choose all that apply.

(1) The left pedestal is being stretched.

(2)The right pedestal is being stretched.

(3) The left pedestal is being compressed.

(4) The right pedestal is being compressed.

Solution

suppose diver is standing at right end of board

assuming tension in left pedestal is T1

and in right pedestal tension is T2

from moment balance about right pedestal

moment due to weight will be in clockwise direction and distance of weight from right pedestal is (5-1.5) / 2 =1.75

so moment due to left pedestal will be in counter clockwise direction so it is in compression

T1*1.5+ 650*1.75

T1= -758.34N (negative means in compression)

so force due to left pedestal = 758.34N and its direction is downward

b) from force balace

force due to right pedestal =650+758.34 = 1408.34N upward so it will be in tension mode

c) (2)The right pedestal is being stretched and (3) The left pedestal is being compressed but if we assume diver is standing on left end of board than ans will be inter changed.