Engineering Mechanics objective questions with answers part4

Q1. Least force required to draw a body up the inclined plane is W sin (plane inclination + friction angle) applied in the direction
(A) along the plane
(B) horizontally
(C) vertically
(D) at an angle equal to the angle of friction to the inclined plane

Q2. The ratio of limiting friction and normal reaction is known as
(A) coefficient of friction
(B) angle of friction
(C) angle of repose
(D) sliding friction

Q3. Which one of the following statements is not correct
(A) the tangent of the angle of friction is equal to coefficient of friction
(B) the angle of repose is equal to angle of friction
(C) the tangent of the angle of repose is equal to coefficient of friction
(D) the sine of the angle of repose is equal to coefficient to friction

Q4. 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

Q5. 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

Q6. Frictional force encountered after commencement of motion is called
(A) limiting friction
(B) kinematic friction
(C) frictional resistance
(D) dynamic friction

Q7. 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

Q8. Select the incorrect statement about friction force for dry surfaces. Friction force is
(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

Q9. If rain is falling in the opposite direction of the movement of a pedestrain, he has to hold his umbrella
(A) more inclined when moving
(B) less inclined when moving
(C) more inclined when standing
(D) less inclined when standing

Q10. A projectile is fired at an angle 9 to the vertical. Its horizontal range will be maximum when 9 is
(A) 0°
(B) 30°
(C) 45°
(D) 60°

Q11. Limiting force of friction is the
(A) ratio of limiting friction and normal reaction
(B) the friction force acting when the body is just about to move
(C) the friction force acting when the body is in motion
(D) minimum force of friction

Q12. Coulomb friction is the friction between
(A) bodies having relative motion
(B) two dry surfaces
(C) two lubricated surfaces
(D) solids and liquids

Q13. 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

Q14. Tangent of angle of friction is equal to
(A) kinetic friction
(B) limiting friction
(C) angle of repose
(D) coefficient of friction

Q15. Kinetic friction is the
(A) tangent of 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

Q16. 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

Q17. The algebraic sum of moments of the forces forming couple about any point in their plane is
(A) equal to the moment of the couple
(B) constant
(C) both are correct
(D) both are wrong

Q18. A single force and a couple acting in the same plane upon a rigid body
(A) balance each other
(B) cannot balance each other
(C) produce moment of a couple
(D) are equivalent

Q19. If three forces acting in one plane upon a rigid body, keep it in equilibrium, then they must either
(A) meet in a point
(B) be all parallel
(C) at least two of them must meet
(D) all the above are correct

Q20. The maximum frictional force which comes into play when a body just begins to slide over another surface is called
(A) limiting friction
(B) sliding friction
(C) kinematic friction
(D) dynamic friction