A 2.0 m long, 200 N uniform ladder, rests with one end against a smooth wall making an angle of 30° with the wall. The coefficient of static friction between the ground and the lower end of the ladder is 0.5. A force F pushes the upper end of the ladder parallel to the wall so that the ladder is on the verge of starting to slip down (static friction has reached its maximum value). The torque of the weight of the ladder relative to the lower end in the ground is: +F a. 200 Nm b. 620 Nm C. 546 Nm d. 400 Nm e None of the above 】

A 2.0 m long, 200 N uniform ladder, rests with one end against a smooth wall making an angle of 30° with the wall. The coefficient of static friction between the ground and the lower end of the ladder is 0.5. A force F pushes the upper end of the ladder parallel to the wall so that the ladder is on the verge of starting to slip down (static friction has reached its maximum value). The torque of the weight of the ladder relative to the lower end in the ground is: +F a. 200 Nm b. 620 Nm C. 546 Nm d. 400 Nm e None of the above 】