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Physics - Static Equilibrium?
A diving board is 3.5m long and has a mass of 14kg. It is supported on one end and at the middle. A diver with a mass of 85kg walks to the other end. What are forces exerted by the two supports on the board.
1 Answer
- WoodsmanLv 71 decade agoFavorite Answer
Sum the moments about either support -- I'll do the middle. (That way the weight of the board and the middle support force have no moments.) Assume diver is at the right end.
Sum of clockwise moments: 85kg•9.8m/s²•1.75m
Sum of ccw moments: Fe•1.75m
These moments must =, or the board would be rotating.
Fe = 85kg•9.8m/s² = 833N DOWN (to produce ccw moment) end support force
Now, we could sum the moments about some other point to find the middle support force, or we can just sum all the forces:
Sum of downward forces: Fe + Fboard + Fdiver = 833N + 14kg•9.8m/s² + 833N = 1803 N
This must = the sum of the upward forces, of which there is 1 !
Fm = 1803 N UP ← middle support force
