Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction: Dry friction is a force that opposes the relative lateral motion of two solid surfaces in contact. Dry friction is subdivided into static friction ("stiction") between non-moving surfaces, and kinetic friction between moving surfaces. With the exception of atomic or molecular friction, dry friction generally arises from the interaction of surface features, known as asperities. Fluid friction describes the friction... Show more

Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other.

There are several types of friction:

Dry friction is a force that opposes the relative lateral motion of two solid surfaces in contact. Dry friction is subdivided into static friction ("stiction") between non-moving surfaces, and kinetic friction between moving surfaces. With the exception of atomic or molecular friction, dry friction generally arises from the interaction of surface features, known as asperities.

Fluid friction describes the friction between layers of a viscous fluid that are moving relative to each other.

Lubricated friction is a case of fluid friction where a lubricant fluid separates two solid surfaces.

Skin friction is a component of drag, the force resisting the motion of a fluid across the surface of a body.

Internal friction is the force resisting motion between the elements making up a solid material while it undergoes deformation

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Class 11 Physics Practice Test: Work, Energy and Power - Friction

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10 Questions

1. The value of the frictional force for a body is always constant when it is static and does not vary with applied force.

Don't KnowMaybeTrueFalse

2. For a body of mass “m” on a rough inclined plane with a constant but arbitrary coefficient of friction as shown in the figure, what is the angle of repose if the net downward force is donated as “F”. Let “g” be the acceleration due to gravity and “u” be the coefficient of friction.

cot θsin θtan θcos θ

3. Consider a block of mass 9.81kg on an inclined surface of the coefficient of friction 0.15 and angle of inclination 30 degrees. What will be its acceleration on the inclined plane if acceleration due to gravity is 9.81 m/s²?

9.81 m/s24.63 m/s23.63 m/s210 m/s2

4. If a box is lying on the floor of a wagon with a coefficient of friction 0.2, what is the maximum acceleration of the wagon for which the box would remain stationary? (Let g = 9.81 m/s²)

2 m/s21.96 m/s24 m/s23.92 m/s2

5. For a body of mass “m” on a rough inclined plane with a constant but arbitrary coefficient of friction as shown in the figure, what is the acceleration on the inclined plane if the net downward force is donated as “F”. Let “g” be the acceleration due to gravity and “u” be the coefficient of friction.

g x sin θg x cos θg (sin θ – u cos θ)g (cos θ – u sin θ)

6. Static coefficient of friction is greater than the kinetic coefficient of friction.

Don't KnowTrueMaybeFalse

7. _____ is known as the motion that would take place under the applied force if friction were absent.

Constrained motionImpending motionUnconstrained motionLinear motion

8. Limiting friction of a body depends on _____

The periphery of the contact surfacesNature of surfacesThe volume of the smaller body on larger surfaceArea of contact of surfaces

9. What are the types of kinetic friction?

Sliding friction, rolling friction and adhesive frictionSliding friction and rolling frictionRolling friction and adhesive frictionSliding friction and adhesive friction

10. The maximum value of static friction when the body is at the verge of starting motion is known as _____

Static frictionImpending motionAngle of reposeLimiting friction