A man in a gym is holding an 8.0-kg kettlebell at arm's length, a distance of 0.55 m from his shoulder joint. What is the torque about his shoulder joint due to the gravitational force on the kettlebell if his arm is held at 30° below the horizontal?

To loosen a rusty nut, a 20.00-N force is applied to the wrench handle at angle ϕ=40° and at a distance of 0.25 m from the nut. Find the magnitude and direction of the torque applied to the nut.

A uniform helicopter rotor blade is 7.80 m long, has a mass of 110 kg, and is attached to the rotor axle by a single bolt. (a) What is the magnitude of the force on the bolt from the axle when the rotor is turning at 320 rev/min? (Hint: For this calculation the blade can be considered to be a point mass at its center of mass.Why?) (b) Calculate the torque that must be applied to the rotor to bring it to full speed from rest in 6.70 s. Ignore air resistance. (The blade cannot be considered to be a point mass for this calculation.Why not? Assume the mass distribution of a uniform thin rod.) (c) How much work does the torque do on the blade in order for the blade to reach a speed of 320 rev/min?

For case A of spin-the-bottle, calculate the magnitude of the torque. Assume that the applied force is 79.0 N and the size of the grid spacing is 3.50 cm.