# Rolling w/out rotation Yo-Yo (torque)

given a Yo-Yo that is rolling on the floor without slipping:

why is the total torque equals to T*r+F_friction*R=I*w rather then

-Tr-F_frictionR=I*w

ive set the direction as followed:

X- direction of T

Y-towards the sky

• I assume you are asking about the torque measured about the center of the yo-yo. What angular direction have you set to be the positive direction? It is arbitrary. – Bill N Feb 27 at 18:31