Physics Help

Hi, I am stuck on the following question:

The ‘Gravitron’ is a circular chamber rotating about a vertical axis. Passengers lie back on couches which line the interior of the chamber, each inclined at 62 degrees to the horizontal. Each couch is allowed to rise a few centimetres as the Gravitron spins faster.
The passengers are 5m from the centre of the ride. Show that the reaction force of the couch on a 76kg passenger is about 1600N as the couch rises. (g = 9.8N/Kg).

I tried calculated the reaction force using f = (mv²)/r but I was unsure how to calculate the v at the instant the Gravitron can rise. I know that it’s the friction that opposes the weight but I don’t know how to calculate that without a coefficient.

Any help would be greatly appreciated.