CHAPTHER 10:Simple machine

Lever…. Type of lever…

Appreciating the innovative efforts in the design of

machines to simplify work

Moment of lever…

Moment of force…

LEVER

- A SIMPLE MACHINE

A lever is a simple machine which turns about fixed point called the fulcrum (F)

when a force called the effort (E) is applied to overcome a resisting force

known as the load (L).

Back

Type of lever Second classlever

First classlever

Third class lever

Back

FIRST CLASS LEVER…

#FULCRUM IS LOCATED BETWEEN EFFORT AND LOAD#

L

F

E

Small force is used to move large loadEffort moves throught a longer distance than the loadEffort is further from the fulcrum than the load is

Example

Example of first class lever~

Scissor Pliers Claw hammer

Crowbar

Back

SECOND CLASS LEVER….

# LOAD IS LOCATED BETWEEN FULCRUM AND EFFORT #

Small force is used to move a large load. Effort moves through a longer distance than the

load Effort is further from the fulcrum than the load is

L

F

E

Example

Example of second class lever~

nutcracker

papercutter

wheelbarrow

Bottle openerBack

THIRD LEVER CLASS….# EFFORT IS LOCATED BETWEEN FULCRUM AND LOAD #

Large force is used to move a small load Load moves through a longer distance than the effort Load is futher from the fulcrum than the effort is

L

F

E

Example

Example of third class lever~

Fishing rod

Ice tong

Broom

Back

The moment of a force…

Moment of Perpendicular distance from a force = Force (N) x the pivot to the force (m)

Formula

++ A force can be used to produce a turning effect to accomplish a desired task. The turning effect of a force is called the moment of a

force…. ++

Back

Meant : The moment of force is the turning affect of force

Moment in a leverIn a lever, the effort and the load produce opposing moments, that is a pair

of clockwise and anticlockwise moments. Since the two moments are balanced, the following formula gives the relationship between the effort,

the load and their respective distances from the fulcrum

Load (N) x Distance of load from the fulcrum (m) = Effort (N) x Distance of effort from the fulcrum (m)

Formula

Back

Appreciating the innovative efforts in the design of

machines to simplify workMany of the simple devices and tools we use everyday to make our work easier are levers. The knife , bottle opener , stapler and even your arm use the principle of the lever. Through the innovative efforts in designing levers, we have scissors , shears , wire-cutter and paper cutter that help us simplify various cutting jobs. Devices that use the principle of the lever can be found almost everywhere, for example, in your classroom, your school canteen and your house. We should appreciate these devices that simplify our work and use them with care.

QUIZ!!

Quiz !!

i. What is lever?

ii. What is meant by moment of force?

iii. Name 2 tools that are in the same class of lever as the human arm. iv. give one main characteristic of first class lever.

The end

Thank

you!!!