Equilibrium Terms

Question 1

Balance

Answer 1

Ability to remain motionless, control equilibrium (static concept)

Question 2

Base of support

Answer 2

Area bound by the outermost regions of contact between a body/support surface/surfaces

Question 3

Centre of gravity

Answer 3

Point around which a system’s weight is equally distributed in all directions

Question 4

Centre of mass

Answer 4

Point around which the mass/weight of a body are balanced

Question 5

Centric Force

Answer 5

Result in linear motion

Question 6

Couple

Answer 6

Pair of equal, oppositely directed forces that act on opposite sides of an axis of rotation to produce torque

Question 7

Dynamic equilibrium

Answer 7

Moving state, balance between applied forces/inertial forces for a body in motion, system accelerating but in control over any external influence

Question 8

Eccentric force

Answer 8

Result in rotational motion (sometimes linear too)

Question 9

Equilibrium

Answer 9

All forces acting on a system are balanced

Question 10

First class lever

Answer 10

Axis of rotation in centre, provides increase in range of motion, stability (can opener, scissors, seesaw)

Question 11

Force arm

Answer 11

Part of lever where force is applied

Question 12

Fulcrum

Answer 12

Point of support/axis about which lever can rotate

Question 13

Lever

Answer 13

1. Rigid body
2. An axis of rotation (fulcrum)
3. Force (where force is applied)
4. Resistance (where effort is centred)
   Effectiveness determined by mechanical advantage

Question 14

Mechanical advantage

Answer 14

Ratio of the force arm to the resistance arm

Question 15

Pure moment

Answer 15

Force couple

Question 16

Resistance arm

Answer 16

Part of lever where resistance is applied

Question 17

Second class lever

Answer 17

Resistance in centre, generate more strength/force, sacrifice speed (wheel barrow, door)

Question 18

Stability

Answer 18

Ability to recover following a disturbance, resistance to disruption of equilibrium (dynamic concept)

Question 19

Static equilibrium

Answer 19

Motionless state, Sum of horizontal/vertical forces and rotary effects = 0

Question 20

Third class lever

Answer 20

Force in centre, increased range of motion/speed of movement (tweezers, stapler)