Physics
posted by Mariam on .
Problem 3 A 40 kg child swings in a swing supported by two ropes, each 3 m long. (a) If the tension in each rope at the lowest point is 350 N,
a. find the child's speed at the lowest point.
b. the force exerted by the seat on the child at the lowest point. (Neglect the mass of
the seat.)
(b) If the tension in each rope is 212 N when the ropes make an angle 30 degree with the
vertical, find the total acceleration of the child.

tensionbottom=mg+mv^2/r
solve for v.
force on set must equal tension...
b.total acceleration is a vector of g downward, and mv^2/r along the radial.
but tension alone, along the radial,
tension=mgcosTheta+mv^2/r
but tension and gravity force=net force
net force=mass*accelerationnet
now you have a vector equation, net force is in the direction given by adding tension along that direction, and mgcosThea along the radial, and mgsinTheta downward. So solve for that net force, then net force=mass*acceleration and solve for acceleration. Not a first grade problem. 
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