Answer to Question #178381 in Physics for ronnel

Question

(a) Find the Net Torque acting on the door and the direction, F1 = 30 lbf , F2 = 73 lbf , F3 = 55 lbf , F4 = 103 lbf , F5 = 88 lbf , F6 = 23 lbf , F7 = 226 lbf and F8 = 55 lbf

Answer 1

If all these torques are applied to the same point at the right angle to the door, we can simply find the net force assuming all odd-numbered forces are positive and even forces are negative:

$$F_\text{net}=\\=30-73+55-103+88-23+226-55=\\=145\text{ lbf}.$$

Assuming door width is 3 ft, the torque is

$$\tau=145·3=435\text{ lbf}·\text{ft}.$$