Answer:
The friction force is reduced to half of the initial
Step-by-step explanation:
 This is a problem of Newton's second law, let's write the equation for the two cases presented 
R radius curve 
 fr = m a 
Where a is the centripetal acceleration 
 a = m v2 / R 
 fr = m v2 / R 
2R radius curve 
 fr2 = m v2 / (2R) 
 fr2 = ½ (m v2 / R) 
 fr2 = ½ fr 
 fr2 / fr = 1/2 
 
The friction force is reduced to half of the initial