In my textbook it's written Work done is always calculated on the displacement of the body parallel or anti-parallel to the direction of the force. And, according to the formula it is : FS\mathbf{F \cdot S} or FscosθFs \cos \theta And work done by torque is given as : τθ\tau \theta Now let's take a case when a cylinder with fixed center of mass and radius RR is rotated with a tangential force FF And it rotates π \pi radians. So, according to the first formula, the displacement is 2R2R but since the the point of application of force has moved , it is right vertically downwards from the initial point of application. So, the angle with the point of application of force and the force vector becomes π2\frac{\pi}{2} And cosπ2=0\cos \frac{\pi}{2}= 0 . And so W=0W = 0 . But the second formula says otherwise, it says that work done is τθ\tau \theta So W=πFRW= \pi FR according to second formula. So yeah, I need to know which is right.