State the laws of limiting friction.
The laws of limiting friction are as follows: (a) The value of limiting friction depends on the nature of the two surfaces in contact and on the state of their smoothness. (b) The force of friction acts tangential to the surfaces in contact in a direction opposite to the direction of relative motion. (c) The value of limiting friction is directly proportional to the normal reaction between the two given surfaces. (d) For any two given surface and for a given value of normal reaction the force of limiting friction is independent of the shape and surface area of surfaces in contact. Coefficient of limiting friction for two given surfaces in contact is defined as the ratio of the force of normal reaction N. 1 r f N
