A. bodies having relative motion
B. two dry surfaces
C. two lubricated surfaces
D. solids and liquids
E. electrically charged particles
Related Mcqs:
- Dynamic friction as compared to static friction is___________________?
A. same
B. more
C. less
D. may be less of more depending on nature of surfaces and velocity
E. has no correlation - Friction force for dry surfaces. Friction force is________________?
Pick up wrong statement?
A. proportional to normal load between the surfaces
B. dependent on the materials of contact surface
C. proportional to velocity of sliding
D. independent of the area of contact surfaces
E. none of the above is wrong statement - The effort required to lift a load W on a screw jack with helix angle a and angle of friction <j) is equal to _________________?
A. Wtan(a + )
B. Wtan(a-)
C. Wcos(a + )
D. Wsin(a + )
E. W (sin a + cos ). - A semi-circular disc rests on a horizontal surface with its top flat surface horizontal and circular portion touching down. The coefficient of friction between semi-cricular disc and horizontal surface is \i. This disc is to be pulled by a horizontal force applied at one edge and it always remains horizontal. When the disc is about to start moving, its top horizontal force will____________________?
A. remain horizontal
B. slant up towards direction of pull
C. slant down towards direction of pull
D. unpredictable
E. none of the above - Limiting force of friction is the__________________?
A. tangent of angle between normal-reaction and the resultant of normal reaction and limiting friction
B. ratio of limiting friction and normal reaction
C. the friction force acting when the body is just about to move
D. the friction force acting when the body is in motion
E. minimum force of friction - Coefficient of friction is the_________________?
A. angle between normal reaction and the resultant of normal reaction and the limiting friction
B. ratio of limiting friction and normal reaction
C. the friction force acting when the body is just about to move
D. the friction force acting when the body is in motion
E. tangent of angle of repose - On the ladder resting on the ground and leaning against a smooth vertical wall, the force of friction will be_________________?
A. downwards at its upper end
B. upwards at its upper end
C. perpendicular to the wall at its upper end
D. zero at its upper end
E. none of the above - The coefficient of friction depends on________________?
A. area of contact
B. shape of surfaces
C. strength of surfaces
D. nature of surface
E. all of the above - Angle of friction is the_______________________?
A. angle between normal reaction and the resultant of normal reaction and the limiting friction
B. ratio of limiting friction and normal reaction
C. the ratio of minimum friction force to the friction force acting when the body is just about to move
D. the ratio of minimum friction force to friction force acting when the body is in motion
E. ratio of static and dynamic friction - On a ladder resting on smooth ground and leaning against vertical wall, the force of friction will be___________________?
A. towards the wall at its upper end
B. away from the wall at its upper end
C. upwards at its upper end
D. downwards at its upper end
E. none of the above
