Answer:
Part a)
[tex]v = \sqrt{\frac{(mg + 2T)R}{m}}[/tex]
Part b)
[tex]F_n = 2(mg + T)[/tex]
Explanation:
Part a)
When child is at lowest position of the swing
then we will have
[tex]mg + 2T = F_{net}[/tex]
here we know that net force on the child is given as
[tex]F_{net} = \frac{mv^2}{R}[/tex]
so we have
[tex]mg + 2T = \frac{mv^2}{R}[/tex]
[tex]v = \sqrt{\frac{(mg + 2T)R}{m}}[/tex]
Part b)
Force exerted by the seat on the child is the normal force and its equation is given as
[tex]F_n - mg = \frac{mv^2}{R}[/tex]
[tex]F_n - mg = mg + 2T[/tex]
[tex]F_n = 2(mg + T)[/tex]