Figure shows a lamina in x-y plane. Two axes z and z' pass perpendicular to its plane. A force F acts in the plane of lamina at point P as shown. Which of the following statements is incorrect ? (The point P is closer to z'-axis than the z-axis). .

Figure shows a lamina in x-y plane. Two axes z and z' pass perpendicul

1.	Figure shows a lamina in x-y plane. Two axes z and z' pass perpendicular to its plane. A force F acts in the plane of lamina at point P as shown. Which of the following statements is incorrect ? (The point P is closer to z'-axis than the z-axis). .
Answer» TORQUE`tau` causedby F aboutz- axisis along`-hatk` Torque `tau` caused by F aboutz'-axisis along`-hatk` Torque `tau` caused by F about z-axisis greater in magnitde to theplanecontainingr and F. totaltorqueis givenbe `tau = tau + tau'` Solution :(A) Considertheadjacentdiagramwhere RGTR Torque`tau`aboutz-axis`tau=rxxf` whichis along `hatk` (B)`tau'=r'xxF` whichis along `-hatk` (c )`\|tau\|_(z)=Fr_(bot )=` magnitudeoftorqueaboutz- axiswhere `r_(bot)` is perpendiculardistancebetweenF and z-axis. SImolarly,`\|tau\|_(z)'=Fr_(bot)'` Clearly `r_(bot)gtr_(bot)'implies\|tau\|_(zgt) \|tau\|_(z)'` (d)we are alwayscalculatingresltant torqueabouta commonaxis . HENCE, totaltorque `tau NE tau+tau'` because `tau and tau` arenotaboutcommon axis.