Question

An evil professor invents a physics problem with no context and gives you the following diagram. Two rigid beams of an unimportant material, one of unknown length r1 and the other of length r2= 2.3 meters are affixed to each other and rotate around a block dot that usually represents a pivot point in problems such as these. For no reason, a force F1= 3.1 N is exerted directly downwards at the end of the first beam. Likewise a force of unknown magnitude F2 is exerted at an unknown angle at the end of the second beam. The y-component of F2 is mercifully give by the professor as 4 N.

a.) What is the sign of the net torque exerted on the system of two beams?

b.) What is the magnitude of the net torque exerted on the system of two beams?

c.) If the angular acceleration of the two beams is 12.3 rad/s^2, what is the moment of inertia of the two beam system?

Answer 1

Both the torque tends to rotate the system in anticlockwise direction. So according to sign convention the sign of torque is positive 6,r, is the torque due to the forces Fi , F, r,-(4 N) (2.3 m = 9.2 Mn (3.1 N) (2 m 6.2 Nm T, = 15.4 Nm

α 12.3 =123=1.25kg·㎡ 1-1 25kg·m"