In physics, a force is a push or pull that can cause an object with mass to accelerate. Force has both magnitue and direction, making it a vector quantity. According to Newton's Second Law, an object will accelerate in proportion to the net force acting upon it and in inverse proportion to the object's mass. An equivalent formulation is that the net force on an object is equal to the rate of change of momentum it experiences. Forces acting on three-dimensional objects may also cause them to rotate or deform, or result in a change in pressure. The tendency of a force to cause rotation about an axis is termed torque. Deformation and pressure are the result of stress forces within an object.