Equilibrium & Friction Balance or slip — the battle begins!Test your grip on forces, tension, and those sneaky friction angles that decide whether things stay still or slide away. 1 / 20 The direction of frictional force is — Opposite to motion Same as motion Perpendicular to motion At 45° to motion Friction always acts opposite to the direction of relative motion between surfaces. 2 / 20 When a body is on a rough inclined plane and just begins to slide, the angle of the plane is — Angle of friction Angle of inclination Critical angle Angle of repose The angle of repose is where limiting friction equals component of weight parallel to the plane. 3 / 20 The resultant of two equal forces acting at right angles is — 2 × each force √2 × each force ½ × each force Zero Using vector addition, resultant = √(F² + F²) = √2F. 4 / 20 Frictional force depends on — Nature of surfaces Area of contact Velocity Volume Rougher surfaces increase friction, smoother ones reduce it. 5 / 20 If the coefficient of friction is zero, the body will — Vibrate Remain at rest Never move Move freely Without friction, there’s no resistance — the body moves effortlessly. 6 / 20 The unit of coefficient of friction is — No unit (dimensionless) N/m² N·m J It’s a ratio of two forces, hence has no units or dimensions. 7 / 20 The limiting angle of repose equals — Half the angle of friction None Angle of friction Twice the angle of friction Both angles represent the same condition at which motion just begins. 8 / 20 Kinetic friction acts when — The body is in motion The body is at rest Motion is impending Force is zero Kinetic (sliding) friction opposes motion after movement begins. 9 / 20 Static friction is always — Less than kinetic friction Greater than kinetic friction Equal to kinetic friction Zero Static friction is stronger — once motion starts, friction drops to kinetic level. 10 / 20 In equilibrium, the algebraic sum of moments about any point is — Constant Infinity One Zero The rotational balance condition requires the sum of all moments to be zero. 11 / 20 When motion is impending, frictional force is — Zero Equal to limiting friction Less than limiting friction Greater than limiting friction At the verge of motion, static friction reaches its maximum — the limiting friction. 12 / 20 The coefficient of friction equals — Frictional force / Normal reaction Normal reaction / Frictional force Frictional force × Normal reaction Product of both It’s the ratio of frictional force to normal reaction, a measure of surface roughness. 13 / 20 Limiting friction is the — Average friction Maximum friction before motion Rolling friction Minimum friction before motion It’s the greatest static friction value just before the body begins to move. 14 / 20 The angle between normal reaction and resultant reaction is called — Angle of inclination Angle of contact Angle of repose Angle of friction The angle of friction shows how much resistance exists between two surfaces in contact. 15 / 20 Friction always acts — At random At 90° to motion Opposite to motion Along motion Friction resists motion, always opposing the direction of relative movement. 16 / 20 The polygon law of forces is used for — Perpendicular forces Concurrent forces Non-concurrent forces Parallel forces It applies to multiple concurrent forces forming a closed polygon when in equilibrium. 17 / 20 If three forces keep a body in equilibrium, they must be — Concurrent Parallel Collinear Equal Three forces in equilibrium must be concurrent and follow the triangle or Lami’s law. 18 / 20 Equilibrium of concurrent forces means all forces meet at a — Point Line Plane Circle Concurrent forces act at a single point, maintaining balance through that common intersection. 19 / 20 The conditions for equilibrium of a rigid body are — ΣF = 0 and ΣM = 0 ΣF = 0 only ΣM = 0 only None For complete equilibrium, both total force and total moment must be zero. 20 / 20 A body is said to be in equilibrium when the resultant of all forces is — Zero Maximum Minimum Constant When all forces cancel each other, the net (resultant) force becomes zero — that’s equilibrium. Your score isThe average score is 0% 0% Restart quiz
