Question

A bridge whose total weight is 4500 N is 20 m long and supported at each end. Find the forces exerted at each end when a
1600 N tractor is located 5 m from the left end.

Answer 1

From the equilibrium:

$$W+F=R_L+R_R$$

Take the moments about left end:

$$R_R (20)=W(10)+F(5)$$

$$R_R (20)=4500(10)+1600(5)$$

$$R_R=2650\ N$$

Thus,

$$4500+1600=R_L+2650$$

$$R_L=3450\ N$$