How to pass derived object in function as base object in C++ [closed]

Answer 1

Shouldn't it be

equationSolver::method1(*this, dt);

Or better yet, make that function to accept a pointer:

class equationSolver{
public:
    static void method1(equation* eq, double dt);
}

Then your original call should work.

Update:

Also you probably want public inheritance:

class simpleMotion : public equation