1. The problem statement, all variables and given/known data Perhaps I am confused by the concept. A toy car starts from rest at a height 4R above the ground and continue to a loop of radius R (frictionless). At a point C (height R from the ground) inside the loop, what is the tangential acceleration of the toy car? 2. Relevant equations I don't think a=alpha*r is quite relevant to this...or a=dv/dt... 3. The attempt at a solution not quite yet. perhaps the gravity is the only thing? Please, explain me of the concept of 'tangential acceleration' and its components.