SIMPLE MACHINE

INTRODUCTION

• Any devices helping to make work easier for us is called a machine.

COMPLEX AND SIMPLE MACHINE

• There are two machines, they are a complex machine and simple machine.

LEVER (PENGUNGKIT)

• A lever is a simple machine made with a bar free to move about a fixed point. The lever consists of parts, load, load arm, fulcrum, effort arm, and effort.

Lever First Class

• Example– Scissors– Pliers– See-saw

Load

distance of effort

fulcrum

distance of load

Second Class

• Example– Wheelbarrow– Bottle can opener– Paper cutter– Nutcracker

Load

distance of effort

fulcrum

effort

distance of load

Third Class

• Example– Human arm– Golf club– Fishing rod

Effort

LoadFulcrum

The relationship between the effort and load and their respective distance from the fulcrum

Load x Load Arm = Effort x Effort arm Mechanical advantage = load/effort

MA = L/E

example

1. Find the effort needed to lift load ?

load(600 N)

60 cm

fulcrum

PULLEY (KATROL)

• The device to assist in lifting an objcts

Three types of pulleys• A Fixed Pulley

Is a pulley that is attached to stationary structure.

• A Movable Pulley

Is pulley that is not attached to a stationary structure

• A Pulley SystemIn a combination of fixed and movable pulley

• Katrol tunggal tetap,• KM = 1

Katrol tunggal bebas, KM = 2

• Katrol ganda dengan tarikan ke bawah KM = 2,

• dihitung dari jumlah tali dikurang 1

Katrol ganda dengantarikan ke atas, KM = 3(jumlah tali)

INCLINED PLANES (BIDANG MIRING)

• An inclined plane is a simple instrument consist of a sloped flat surface such as wedges, screws, and bolts.

The MA of an inclined plan is equal to the length of the slope (s) divided by the height (h) of the inclined plane

h

sMA

WHEEL (RODA)

• Bicycle rider can set the ratio of the chain wheel (front gear) and freewheel (back gear) to adjust to the road being travelled

• The smaller the back gear, the heavier the pedalling, but the large the rate of acceleration

• The larger the back gear, the lighter the pedalling, but the slower the bicycle will move