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MCQ
1641. Least force required to draw a body up the inclined. plane is W sin (plane inclination + friction angle) applied in the direction-
along the plane
horizontally
vertically
at an angle equal to the angle of friction to the inclined plane
1642. The ratio of static friction to dynamic friction Is always-
equal to one
stream line
steady
turbulent
None
The ratio of static friction to dynamic friction is always greater than one. Friction: Friction is an opposing force that comes into play when the body is actually moving (slide or roll) or even tries to move over the surface of another body. Static friction (Fs): The opposing force that is active when the body tends to move over the surface, but the actual motion is vet not started. Kinetic friction(Fk): Kinetic or dynamic force is an opposing force that is active when the body is actually moving on another surface.
1643. The ratio of limiting friction and normal reaction is known as-
coefficient of friction
angle of friction
angle of repose
sliding friction
1644. Kinetic friction is the-
tangent of angle between normal reaction and the resultant of normal reaction and the limiting friction
ratio of limiting friction and normal reaction
the friction force acting when the body is just about to move
the friction force acting when the body is in motion
1645. Dynamic friction as compared to static friction is-
same
more
less
maybe less of more depending on nature of surfaces and velocity
1646. A heavy ladder resting on floor and against a vertical wall may not be in equilibrium, if-
the floor is smooth, the wall is rough
the floor is rough, the wall is smooth
the floor and wall both are smooth surfaces
the floor and wall both are rough surfaces
1647. The friction experienced by a body, when at rest, is known as-
station friction
dynamic friction
limiting friction
coefficient of friction
1648. A block sliding down an inclined plane has acceleration - acceleration due to gravity.
less than
greater than
same as
none of the above
1649. The angle of inclination of the plane at which the body beings to move down the plane is called-
angle of friction
angle of repose
angle of projection
gone of those
1650. On a ladder resting on smooth ground and leaning against vertical wall, the force of friction will be-
towards the wall at its upper end
away from the wall at its upper end
upwards at its upper end
downwards at its upper end
1651. Coefficient of friction is the-
angle between normal reaction and the resultant of normal reaction and the limiting friction
ratio of limiting friction and normal reacion
the friction force acting when the body is just about to move
the friction force acting when the body is in motion
1652. Which one of the following statements is not correct-
the tangent of the angle of friction is equal to coefficient of friction
the angle of repose is equal to angle of friction
the tangent of the angle of repose is equal to coefficient of friction
the sine of the angle of repose is equal to coefficient to friction
1653. The coefficient of friction depends on
area of contact
shape of surfaces
strength of surfaces
nature of surface
1654. Tangent of angle of friction is equal to-
kinetic friction
limiting friction
angle of repose
coefficient of friction
1655. Coulomb friction is the friction between-
bodies having relative motion
two dry surfaces
two lubricated surfaces
solids and liquids
1656. Limiting force of friction is the-
tangent of angle between normal reaction and the resultant of normal reaction and limiting friction
ratio of limiting friction and normal reaction
the friction force acting when the body is just about to move
the friction force acting when the body is in motion
1657. Angle of friction is the-
angle between normal reaction and the resultant of normal reaction and the limiting friction
ratio of limiting friction and normal reaction
the ratio of minimum friction force to the friction force acting when the body is just about to move
the ratio of minimum friction force to friction force acting when the body is in motion
1658. Frictional force encountered after commencement of motion is called-
post friction
limiting friction
kinematic friction
dynamic friction
1659. Pick up wrong statement about friction force for dry surfaces. Friction force is-
proportional to normal load between the surfaces
dependent on the materials of contact surface
proportional to velocity of sliding
independent of the area of contact surfaces
1660. On the ladder resting on the ground and leaning against a smooth vertical wall, the force of friction will be-
downwards at its upper end
upwards at its upper end
perpendicular to the wall at its upper end
zero at its upper end