Question

A yoyo of mass m=2 kg and moment of inertia ICM=0.04 kg m2 consists of two solid disks of radius R=0.2 m, connected by a central spindle of radius r=0.15 m and negligible mass. A light string is coiled around the central spindle. The yoyo is placed upright on a flat rough surface and the string is pulled with a horizontal force F=12 N, and the yoyo rolls without slipping.

(a) What is the x-component of the acceleration of the center of mass of the yoyo? (in m/s2)

a=

unanswered
(b) What is the x-component of the friction force? (in N)

f=

Answer 1

a=F.(R+r)/(I/R+m.R)=7
f=F-m.a =-2 BUT you write 2 (without the minus (-) sing)

Answer 2

Shouldn't the acceleration be less than 6 m/s^2? The yoyo should not accelerate more than what is provided by the 12N force or a(max)= F/m = 12/2 = 6 m/s^2 ?