A 70-kg person stands on the end of a 40-kg diving board whose support is 3m away. The torque exerted on the support is:
a. 270N*m
b. 2058N*m
c. 2646N*m
d. 3234N*m

Question

A 70-kg person stands on the end of a 40-kg diving board whose support is 3m away. The torque exerted on the support is:
a. 270N*m
b. 2058N*m
c. 2646N*m
d. 3234N*m

anonymous · Answer

The answer is C, not B as your method would conclude. I think the fact that the board has mass changes things.

anonymous · Answer

Yeah, it should be C.

If the board had negligible mass, @shamim would be right.

The only change in this case is that you also have to calculate the torque acting due to the board.

So you need to add: 40*9.8*1.5 = 588 N*m for the board CM which is in the middle of the board.

Just the person is what you've already got: 2058 N*m

2058 N*m + 588 N*m = (c) 2646 N*m