Question

A lightweight diving board is supported by two pillars. One is at the end of the board and the other is 2.30 m away. A 75-kg person is standing on the board at such a location that the pillar at the end (pillar #1) of the board exerts a 890-N force downward. Determine the following.

(a) distance the person is standing from the end pillar (pillar #1) 5.09

(b) magnitude of the upward force exerted by the second pillar (pillar #2)

Struggling with the second part if anybody is able to help, thank you!

Answer 1

Given diving board is light weight ,so we can ignore weight of diving board

First take moment about Pillar B

890*2.3 -Weight of man*distance from Pillar B =0

890*2.3- 75*9.81 *X =0

X =890*2.3/(75*9.81)

X=2.782m

so Total distance from end pillar(Pillar A) =2.3+2.782=5.082m

(a)ANSWER: = 5.082m

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Now take moment about Pillar A

Upward force at B*2.3 -Weight of man *5.082 =0

F_b*2.3 =75*9.81*5.082

F_b =1625.69 N

ANSWER: =1625.69N

Alternate way

Just Add both downward forces

F_b =890+75*9.81 =1625.75 N

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