An airplane flies at 120 km/h takes a 20 degree turn on 30 seconds.

a) What is the centripetal acceleration ?
b) from where does it get it's centripetal acceleration ?

How far does it go in 30 seconds (1/2 minute)?

(1/2)min * 1 hr/60 min *120,000 m/hr
= 1000 meters

360/20 = 18
the circumference of the turn = 18,000 meters

2 pi r = 18,000
r = 2865 meters

Ac = v^2/r = (120,000/3600)^2 / 2865
= .388 m/s

Check my arithmetic !!

usually plane banks in a turn so a component of the lift on the wings is pointed toward the center of the circle.