2.7 A bus is accelerating uniformly forward along a level road. A book lying on the floor experiences negligible friction while the bus accelerates. An identical book lying in the middle of a flat seat in the bus experiences a significant frictional force and remains at rest on the seat as the bus accelerates. 2.7.1 Define frictional force. (2) 2.7.2 Is there a resultant (net) force acting on the book that is on the floor as the bus accelerates? Explain your answer. (2) 2.7.3 Describe the motion of the book on the floor as observed by a passenger on the bus while the bus is accelerating forward. (2) The mass of each book is 0,1 kg. The coefficient of static friction between the book and the seat is 0,4. 2.7.4 Calculate the magnitude of the frictional force that must be overcome for the book to slide. (4) 2.7.5 Calculate the magnitude of the minimum forward acceleration of the bus that would cause the book on the seat to slide. (3) GRU