A 5,000 kilogram granite boulder rests on a 13° slope where, halfway down the slope, traffic speeds along a busy two-lane road. What is the force acting on the granite?
+33653 There are three forces acting on it. The force of gravity (mass*g) is one. The reaction of the road surface on the boulder is another. The static friction of the road surface is the other - this will be given by μ*mass*g*sin(13°), where μ is the coefficient of static friction between the boulder and the road. The net force is zero, as the boulder isn't accelerating (unless one of the cars slams into it!).
+33653 There are three forces acting on it. The force of gravity (mass*g) is one. The reaction of the road surface on the boulder is another. The static friction of the road surface is the other - this will be given by μ*mass*g*sin(13°), where μ is the coefficient of static friction between the boulder and the road. The net force is zero, as the boulder isn't accelerating (unless one of the cars slams into it!).
