Question

Consider a horizontal, uniform board of weight 125 N and length 4 m that is supported by vertical chains at each end. A person weighing 500 N is sitting on the board. The tension in the right chain is 250 N
What is the tension in the left chain?

a. 250 N
b. 375 N
c. 500 N
d. 625 N
e. 875 N

Answer 1

Answer:

b. 375 N

Explanation:

System of forces in balance

ΣFy = 0 Equation (1)

Forces acting on the board

T₁: Tension in the  left chain ,  vertical and upward

T₂ = 250 N : Tension in the right chain ,  vertical and upward

W₁ = 125 N : Weight of the  board , vertical and downward

W₂ =  500 N : Weight of the  person , vertical and downward

Calculation of the T₁

We apply the Equation (1)

ΣFy = 0  

T₁+T₂-W₁-W₂ = 0

T₁ = -T₂+W₁+W₂

T₁ = -250 N+ 125 N+ 500 N

T₁ = 375 N