How do I calculate the strain in a roller coaster? (Physics)?

stress = force / Area Force is in Newton (g m/s^2) Area in m^2 convert kg to newton = 1 x 10^3 x 9.81 =9.81 x 10^3 if each person weights 70 kg ( 70*9.81x10^3)*84 = 57.68 x 10^6 N ( i dont know why you times it by 3) assuming you have made an error in your calculation. Area = 0.9 m thus stress = (57.68 x 10^6 N) / (0.9 m^2) = 64.09 x 10^6 N/m^2 N/m^2 = 1 pascal Now to workout the strain you need the young's modulus of the material.. for steel is normally (29 x10^6) Young's modulus E = stress / strain thus strain = stress /E = (57.68 x 10^6)/(29x10^6) = 1.99 dimensionless strain = change in length / original length .. if you know the original length you can workout the change in length.. Always check your units.. It's very important.. you wont make mistakes