Mechanisms MOMENTS AND LEVERS Moments Boom Counter balance

Mechanisms MOMENTS AND LEVERS

Moments Boom Counter balance weight In order to understand Mechanisms better, we need to understand pivots, moments and equilibrium.

Equilibrium When something is balanced it is said to be in equilibrium. Pivot point Or fulcrum Fulcrum

Moments The Moment of a Force is the force multiplied by the distance from the pivot point. Distance (d) Fulcrum Moment = F x d Force (F)

Moments Torque may be represented as shown. Force Pivot Point Torque (turning force) = Force x Distance

The Principle of Moments states, that for there to be equilibrium, the clockwise moments must equal the anti-clockwise moments. Balanced when f 1 xd 1 = f 2 xd 2 Clockwise Moments = F 2 x d 2 Anti-clockwise Moments = F 1 x d 1 If F 2 x d 2 = F 1 x d 1 there is equilibrium

f 1 d 1 Clockwise Moments = F 2 x d 2 = d 2 f 2 20 nx 1 m = 20 Nm Anti-clockwise Moments = F 1 x d 1 = 10 Nx 2 m = 20 Nm The Principle of Moments If F 2 x d 2 = F 1 x d 1 there is equilibrium 20 Nm = 20 Nm, Therefore, the loaded beam is in equilibrium.

Levers lever Definition A lever is a rigid rod, pivoted about a fixed point or axis, which is known as the fulcrum Effort Load Fulcrum

Levers There are three types or class of lever. Class one Examples: Seesaw Crow bar Scissors Examples: Wheelbarrow Class two Micro switch Brake pedal Example: Shovel Class three Fishing rod Forearm muscles

Levers Class One Levers See-saw Crowbar

Levers Class Two Levers Brake pedal Wheel Barrow

Levers Class Three Levers Shovel Fishing rod

Mechanical Advantage = Load Effort Man lifting a Stone with a Lever Load Fulcrum

Mechanical Advantage - Calculation Effort To raise a weight 400 N. It was found that the weight could be lifted with an effort of 100 N. What is the Mechanical Advantage of the mechanism? Load Mechanical Advantage = Load Effort = 400 N = 4: 1 100 N or 4

Velocity Ratio Distance moved by effort Lever Load The Velocity Ratio = Distance moved by effort Distance moved by load Distance moved By load

Velocity Ratio – Calculation Distance moved by effort 85 cm The 500 N weight is moved with an effort of 100 N. The distance moved is shown What is the Velocity Ratio of the mechanism? Velocity Ratio = distance moved by effort = 85 cm distance moved by load = 17 cm = 5: 1 or 5 Distance moved by load 17 cm