Hi all here is the question I need to justify. Please see the attached file with the question. I would simply like to use the formula (theta)=tan(^-1)[(v^2)/gr] to solve the angle. This gives the correct answer. Now my teacher however solves it using a different vector method and says in order for me to use this in the exam I will need to provide proof that this is an acceptable solution. I have found some stuff online that says; for any object moving at constant velocity on a horizontal surface the centripetal force will be the same as the force of friction. What else can I say to justify this? (My teacher is very stubborn).