Which of the following is not a type of friction?
Gravitational friction
Friction is the resistance offered at the contact between two surfaces when one tends to move or moves relative to the other. It is a surface/contact phenomenon and is conventionally classified according to the nature of that relative motion.
The genuine categories of friction include:
- Static friction — the resistance between two surfaces that are at rest relative to one another; it self-adjusts up to a limiting value before motion begins.
- Kinetic (dynamic/sliding) friction — the resistance when the surfaces are actually sliding over each other; usually a little less than the limiting static value.
- Rolling friction — the (much smaller) resistance experienced when a body such as a wheel or ball rolls over a surface.
- Fluid/film friction — the resistance arising in a lubricating film separating the surfaces.
By contrast, gravitational friction is not a recognised type of friction, so it is the odd one out and the correct answer. Gravity is a body force acting at a distance; it can produce the normal reaction that presses surfaces together (and thereby influences the friction force through F = μN), but gravity itself is not a contact resistance and does not constitute a class of friction.
- Static friction, kinetic friction, and rolling friction are all standard, well-defined types, so none of them is the answer.
Thus the term that is not a type of friction is gravitational friction.
Similar Questions
A body is resting on a rough inclined plane. If the frictional force is equal to the component of weight along the plane, the body is in:
Which type of friction occurs when surfaces are lubricated with a fluid?
Under which scenario is a body on an inclined plane most likely to slip when subjected to a parallel force?
If a block slides down a rough plane inclined at 30° with a coefficient of friction of 0.2, the net acceleration is:
With an increase in angle of the inclined surface, the maximum angle at which a body starts sliding down the plane is called ___________.
A block of weight (W) rests on a rough inclined plane with an angle of inclination α shown in the figure. The coefficient of friction between the block surface and the plane is μ, R is the normal reaction perpendicular to the inclined plane. A force (P) is applied parallel to the plane to prevent the block from sliding down. Which of the following represents the minimum value of (P) required to maintain equilibrium?
Important Questions from Friction
A steel wheel of 600 mm diameter rolls on a horizontal steel rail. It carries a load of 500 N. The coefficient of rolling resistance is 0.3 mm. The force in N, necessary to roll the wheel along the rail is:
Which of the following option is CORRECT about the methods used to reduce the friction?
Which of the following is NOT a law of static friction?
If we push the break of car then car will begin to slide when:
An elephant is stopped by a rope wound twice around the rough trunk of a tree. If the elephant exerts a pull of 1000 kgf, the minimum force required to stop the elephant is_________. (Coefficient of friction between the rope and the tree is 0.3)
