MECHANICAL ADVANTAGE

K WARNE

Moment of Force The moment of a force about a point is the ……………….of the

magnitude of the force and the perpendicular distance from the point to the line of the force.

Calculate the moment of the force, or ……….., due to each force when several forces act on the same object using the equation:

= F … r

F

Calculating Torque

F 2

F1

F2

= F x r = (F1x …1) + (F2x …2)

When calculating torque the ………….of all the PERPENDICULAR FORCES must be used.

TORQUE

Equilibrium For an object to be in equilibrium BOTH the sum of the ……………..

acting on the object and the sum of the …………….of the forces must be ZERO.

Solve problems involving objects in equilibrium.

F2

F3F1

FORCES (Linear) in equilibrium .: F1 + F2 + F 3 = ……

MOMENTS in equilibrium .: ……………. a fulcrum. (F1)

(F1….) + (F2…..) + (F3……) = 0

x1

x2

If a 60 Kg person stands 2 meters from one end of a 3 meter scaffolding plank what force is needed to support each end of the plank?

Equilibrium Know that for an object to be in equilibrium BOTH the sum of the

FORCES acting on the object and the sum of the MOMENTS of the forces must be ZERO.

F2

FORCES (Linear) in equilibrium .: F1 + F2 + F 3 = 0

MOMENTS in equilibrium .: Choose a fulcrum. (F1)

(F1.0) + (F2.x1) + (F3.x2) = 0

x1 x2

If a 60 Kg person stands on one end of a 3 meter scaffolding plank what force is needed to support him on the other end of the plank if the plank is balancing on a fulcrum 2m away from the 60kg person?

F1

60kg

2m

Levers• Describe the terms “load” and “effort” for a lever• Define “mechanical advantage” as the ratio of

“load/effort” and calculate the mechanical advantage for simple levers

…………..................

E

L……

.......

.

If in equilibrium: …… x ….. = …… x …..

Mechanical Advantage

Mechanical Advantage is the ………...of the LOAD to the EFFORT.

Apply the concept of mechanical advantage to everyday situations.

Mechanical Advantage =

?

N

……..

……..

Types of Levers

The three classes of lever are shown here.

By considering the mechanical advantage of each decide which give the best.

(Consider a 1m bar being used for each type.)

Class 1Effort ..........

Class 2

Effort

Load

Class 3

................

Load ..............

..............

................

..........

Examples of Levers