You are driving an automobile and you are making a left turn at constant speed. A package slides across the seat as a result of the turn. Which of the following is true?

 

a)There would be no motion of the package relative to the seat if the force of friction were sufficiently great between the package and the seat.

 

b)There would be no motion of the package relative to the seat if there were no forces acting on the package.

 

c)Frictional forces are not important in situations like this.

Answer : (a) There would be no motion of the package relative to the seat if the force of friction were sufficiently great between the package and the seat.

According to Newton's First law of motion (Law of inertia) : Any object at rest or moving with constant velocity will sustain its state of motion unless and until any unbalanced external force acts on it.

When you make the turn - The whole car experiences the force due to car but the package doesn't experience any external force (if we ignore the friction) - Thus the package will slide because it tries to sustain its motion along the straight line while the car is making turn.

Step-by-step explanation

When the automobile and you are making a left turn at constant speed, A package slides across the seat as a result of the turn. 

Because, When the automobile is trying to make turn - There will be no force acting on the package due to the car and Hence due to inertia, The package will try to sustain its motion along the straight line - Hence the package will slide across the seat.

But if there is frictional force between the seat and the package - This frictional force will provide required centripetal force for the package to move along the turn with the car and hence prevents the package from sliding.

Please note that the frictional force always opposes the motion.