Another circular motion question

Mar 2017
5
0
Hi, I've got another question.

question and diagram - https://ibb.co/daf21F

Im doing question 2aiiia

I thought that since radial force = mv²/r = 64m N and the transverse force = m*angular acceleration = 0, The magnitude and direction of the force is 64m N towards the centre. However, according to the book the answer is 73.8m N towards the centre.

Where have I gone wrong?
 
Aug 2008
113
35
$F_c = F_r - mg \implies \dfrac{mv^2}{r} = F_r - mg \implies F_r = \dfrac{mv^2}{r}+mg$

$F_r = m\left(\dfrac{v^2}{r} + g\right)$

recalculate ...