Answer:
a = 5.256 m / s² with the vertical direction upwards and T = 1090.8 N
Explanation:
to find the acceleration we must use Newton's second law, in the lowest part of the motion
T - W = m a
where the acceleration is centripetal
a = v² / r
let's calculate
a = 4.51² / 3.87
a = 5.256 m / s²
As the acceleration is centripetal it is directed towards the center of the circle, which in the lower part coincides with the vertical direction upwards.
Let's find the tension of the rope with the first equation
T = W + m a
W = m g
let's calculate
T = 710 + 710 5.256 / 9.8
T = 1090.8 N