Physics · SYSTEMS OF PARTICLES AND ROTATIONAL MOTION

In the system shown in Figure, a uniform bar AB of length 70 cm and weight \( W \) is supported on knife edges \( K_1 \) and \( K_2 \) located at 10 cm from ends A and B respectively. A load \( W_1 \) is suspended at P, 30 cm from end A. If the reactions at \( K_1 \) and \( K_2 \) are denoted as \( R_1 \) and \( R_2 \), taking the moments about the centre of gravity G of the bar yields which of the following equilibrium conditions?

1. \( R_1(K_1G) - W_1(PG) - R_2(K_2G) = 0 \)
2. \( R_1(K_1G) + W_1(PG) - R_2(K_2G) = 0 \)
3. \( -R_1(K_1G) - W_1(PG) + R_2(K_2G) = 0 \)
4. \( -R_1(K_1G) + W_1(PG) + R_2(K_2G) = 0 \)