physics
posted by Anonymous .
A uniform rod (AB) of mass 80kg and 1.0m lenght is supported on the 2 knife edges placed 15.0cm from its ends. what will be the reactions at these support when a 20kg mass is suspend 10cm from the midpoint of the rod.(workings and diagram)

sum vertical forces. Let fl be the knife edge left support, and fr be the right support.
fl+fr=80+20 in kg
sum moments about the left knife edge.
0=20kg(501510)+80(5015)Fr*70
solve for the force right. then in the other equation lf.
Now in newtons, multiply by 9.8, kg is not a force.