Strength of materials question.?

Question

There is a log, 16 fit in length and a person is standing on the middle of it (8ft mark). He weighs 225 lb. What is the max bending moment?? 225 lb.ft, 450 lb.ft 622.5 lb.ft or 900 lb.ft?

Answer 1

Well, a 16 foot log strong enough to support a 225lb person will probably weigh more than 225lb, so it seems silly to be ignoring the weight of the log, but since it is not given, I guess we have to ignore it.

If the load in the center is 225lb (ignoring the log itself) the reaction at each end will be 1/2 of 225 or 112.55lb

112.5lb x 8ft = 900lb,ft

Answer 2

If the log is floating on water, the maximum bending moment is 450 ft-lbs.

If the log is simply supported at the ends like a beam, the maximum bending moment due to the person is 900 ft-lbs.