Question

A man of mass 72 kg is standing at the end of the diving board of mass 28 kg as shown in figure. A and B are two supports for the board. $[g=10m/s^2]$

• A. Force on support A is 2520 N
• B. Force on support B is 3870 N
• C. Force on support A is 2870 N
• D. As man moves towards A, force on support B decreases.

Answer 1

Answer: (B), (C), (D)

The correct options are
B Force on support B is 3870 N
C Force on support A is 2870 N
D As man moves towards A, force on support B decreases.


By torque equilibrium about B

$N_A\times 1=280\times 1.25+720\times 3.5$

$N_A=2870$ N

By balancing the forces in the vertical direction,
$N_B=N_A+280+720\Rightarrow N_B=3870N$
As the man moves towards left, to balance torque, $N_A$ decreases. So, to balance, the force in the vertical direction, $N_B$ also decreases.