While teaching the topic ‘Friction’ to Class V students, a teacher gave a number of examples to explain that friction is also useful to us in many ways. Which one of the following exam ples was quoted by her incorrectly?
Friction is a force that opposes the relative motion between two surfaces of objects in contact. The force of friction always acts in a direction opposite to that of the applied force. Friction is due to irregularities on the surfaces of the objects in contact. Friction depends on the smoothness of the surfaces in contact. The force of friction depends on the nature of the surfaces in contact. Since friction is a type of force, it is measured in Newton (N). Examples of friction:
We are able to walk because of frictional forces between ground and our feet.
We are able to write because of friction between ball point and the paper surface.
Nails and screws stick to wall surfaces because of friction.
Lighting a match stick is because of friction between match stick and the side surface of match box.
Wear and tear of soles of our shoes is due to friction.
When a tyre deflates, it is difficult to move the vehicle because of increased friction between the tyre and road surface.
Machines gets heated up and produce noise because of friction.