Question

Frictional force always acts in which direction?
(a) Opposite to that of the object in motion.
(b) In the same direction as that of the object in motion.
(c) In any direction
(d) None of the above

Answer 1

Hint: Well, the question demands definition of frictional force because with the help of its definition one will be able to find out about the direction of this force. If we try to consider examples in our daily life then, also we can answer it.

Complete answer:
Frictional force: A frictional force is an opposition which can be to any action. There can be an opposition to a current which we name as resistance and for the opposition to the speed of any object is called frictional force. If we see then we will find many examples in our life which will explain frictional force clearly. The duty of frictional force will be restricting and force which helps in moving the object forward. We will take an example of a cube which is a little heavy in weight. We will find that if we are applying force from its back then, it will move forward because its opposition force which tries to stop the cube is less than our force. But in case there is a cube with much greater weight which can only shift its position by a crane then this means that its frictional force is greater than our force applied to it. In a circuit also, we find a resistance that is generated in order to balance current in a circuit. The function of this resistance is to reduce the current flowing in a circuit by applying a specific small value of it.
In the following example we can see frictional force acting against the force of a human.

Frictional force working as a resistance force is shown in the following diagram.

Hence, the correct option is (a) that the frictional force always moves in the opposite direction which is actually opposite to the direction of the object in motion.

Note:
Frictional force works as an opposition. If we think in a way that you are in a library and two students want to have the same book then, we will find that they both will try to keep a book by applying force on it. By that force the second student will try to take it back from him. The frictional force will be seen here as a back force applied by a second student for the same book. The shoes are a good example for understanding frictional force. The dents made on the below of a shoe will prevent the runner before slipping on the floor. In both cases frictional force is considered as a force opposite to the direction of normal force applied by us.