Moment of force, torque
- Find the torque about the origin when a force of 3j N acts on a particle whose position vector is 2k m. Answer: 3. -6i N m Torque vecτ=vec r×vec F . vecτ=2hat k×3hat j=6(hat k×hat j)=6(-hat i)=-6hat i\ N m Since hat j×hat k=hat i , reversing th... 1
- A solid cylinder of mass 2 kg and radius 4 cm is rotating about its axis at the rate of 3 rpm. The torque required to stop after 2π revolutions is : Answer: 1. 2×10⁻⁶ N m Find the angular deceleration from the rotation kinematics, then use τ=Iα . ω₀=3 rpm =3×2π/60=0.1π rad/s. Angle turned... 1
- The moment of the force, F=4 i+5 j-6 k at (2, 0, -3), about the point (2, -2, -2), is given by Answer: 4. -7hat i-4hat j-8hat k Moment (torque) about a point: vecτ=vec r×vec F , where vec r goes from the point to the point of applicati... 1