The equation of torque is:
[tex]\tau=r\times F \times sin(\theta)[/tex]
where r is the distance from the fulcrum and F is the force. Since the problem states that our seesaw is balanced this means that the angle is zero and so theta = zero and sin(0)=1 therefore we can ignore that part of the equation since it's 1. Furthermore since the problem states that it is in equilibrium this means that the left side is equal to the right, mathematically :
[tex]\tau_1=\tau_2\\\\r_1 \times F_1 = r_2 \times F_2[/tex]
Let the left be 1 and right be 2. In order to calculate the amount of torque the right side is providing to the system we need to first find out the distance (r2) that the person on the right is sitting with respect to the fulcrum and so:
[tex]400N \times 1.5m=r_2 \times 300N\\\\\frac{400N \times 1.5m}{300N}= r_2\\ \\r_2=2m[/tex]
And now we will calculate the torque on the right side:
[tex]\tau_2=r_2 \times F_2\\\\\tau_2= 2m \times 300N = 600 mN = 600 kgm^{2}s^{-2}[/tex]
600 mN
