Please answer the first question only: \"For steady conditions, what can you say
ID: 1783861 • Letter: P
Question
Please answer the first question only:
"For steady conditions, what can you say about the moment about the boat's center of mass from this force above the water surface compared with the moment generated below the surface."
The wind force on the sail of a sailboat causes the boat to lean over. For steady conditions, what can you say about the moment about the boat's center of mass from this force above the water surface compared with the moment generated below the surface. Explain why sailboats have keels, centerboards, or daggerboards. 2.Explanation / Answer
Okay, So above the water surface, we are dealing with mast and below the water surface, we are dealing with keel. Let's first understand what is moment. In equation term, moment is simple force multiplied by distance. Higher the distance, higher will be the load due to moment.
Lets assume boat's center of mass is somewhere located on the mast at distance d . Then moment created will be
FWIND * d where FWIND is the wind force being applied on the mast. Due to this, the boat will tip to one side. As the boat tips to one side, the keel weight which was acting vertically downward will go off center. Remeber, weight is also a force. Now, the tipping moment created by the wind over the water is equal to the moment created by the keel which is given by
FG * D where FG is the weight force.
The boat will continue to tip until
FWIND * d = FG * D
One important thing to take care is that this tipping moment is dependent on height, area of mast and velocity of wind and as the boad tip over to either side, the exposed area and height of mast to the oncoming wind will decrease which will decrease the length of moment (d) , it will decrease the moment also.