WORK SIMPLE MACHINES GRADE 66 Mrs Figoten WORK

WORK & SIMPLE MACHINES GRADE 66 Mrs. Figoten

WORK = FORCE X DISTANCE Joules = newtons (N) X meters (m)

CALCULATING WORK The crane uses 30 newtons of force to lift the iron block 8 meters. Work done = Force x Distance moved = 30 newtons (F) x 8 meters (D) = 240 Joules How much work was done? -----------------------Because the block is held up high, it becomes: potential energy = 240 J (due to gravity) gravity If the mass then falls freely to the ground, just before it hits the ground, it’s. . . 240 J of kinetic energy

INCLINED PLANE v Flat surface with 1 end higher than other v Used to gradually raise or lower objects MECHANICAL ADVANTAGE (MA) INPUT FORCE DISTANCE Longer Plane = More Distance v EFFICIENCY v Friction reduced if surfaces of plane & load are smooth

Examples of INCLINED PLANES http: //www. smartown. com/sp 2000/machines 2000/inclinedplane. htm

WEDGE Type of inclined plane v Has 1 or 2 sloping sides v Force applied to wide end v Narrow end driven into object– push object apart v MECHANICAL ADVANTAGE (MA) INPUT FORCE DISTANCE Longer Point/Edge = More Distance v v EFFICIENCY Friction reduced if edge sharper

Examples of WEDGES

SCREW Type of inclined plane v Wrapped around a rod v Direction of force changed v Amount of force increased v MECHANICAL ADVANTAGE (MA) INPUT FORCE DISTANCE More threads = More Distance v EFFICIENCY v Increased when threads closer

Examples of SCREWS

LEVER v Does work by turning around FULCRUM (fixed point) v Force applied to do the work = EFFORT v Force created by LOAD when trying to move it = RESISTANCE v EFFICIENCY GREATEST WHEN WORK REQUIRES THE LEAST EFFORT

MECHANICAL ADVANTAGE (MA) INPUT FORCE DISTANCE Longer Effort Arm = More Distance load rm a t r o effort fulcrum

LESS DISTANCE BETWEEN LOAD & FULCRUM LESS EFFORT NEEDED TO DO THE WORK

TYPES OF LEVERS

FIRST CLASS LEVER

SECOND CLASS LEVER

THIRD CLASS LEVER

Summary of LEVER CLASSES 1 st Class 2 nd Class How do you know what class a lever is? By whether the fulcrum, load, or effort is in the center. 3 rd Class Fulcrum= Pivot Point Effort force = input force Load (Resistance) = output force

WHEEL & AXLE v Large wheel fixed to smaller wheel (or shaft) called an axle v Both turn together v Effort usually on larger wheel, moving load of axle MECHANICAL ADVANTAGE (MA) INPUT FORCE DISTANCE Turning larger wheel = More Distance

Think of as lever rotating in circle around center fulcrum v Like steering wheel (larger wheel) on column (axle) v Wheel & axle turn together EFFICIENCY: v Reduced friction with lubricant

HOW DOES WHEEL & AXLE WORK?

PULLEY Wheel with groove v Allows rope to ride on wheel without slipping off MECHANICAL ADVANTAGE (MA) INPUT FORCE DISTANCE Rope around more wheels = More Distance

TYPES OF PULLEYS FIXED PULLEY (like clothesline or flagpole) v Pulley stays in one position v Moves LOAD up, down or sideways v Changes v Does DIRECTION of force not reduce EFFORT

TYPES OF PULLEYS MOVABLE PULLEY (for lifting or lowering heavy objects v Moves along with LOAD v Reduces v Increases EFFORT DISTANCE

Examples of PULLEYS

v v Wheels with teeth, so one turns the next SMALLER gear turns FASTER than larger gear One gear makes other gear beside it turn in OPPOSITE DIRECTION Speeds things up, slows them down, changes direction of force GEARS

COMPOUND MACHINE Compound machines are made of 2 or more simple machines.

KIDS’ INVENTIONS Illustrating… COMPOUND MACHINES Made of at Least 2 SIMPLE MACHINES

This is the Chore 3, 000. He can clean your room. It can take the trash out and do other chores. He is made of gears, screws and pulleys. .

This simple machine is The Kids’ Chore. Our simple machine does a lot of stuff such as recycles cans and then washes them, and then has them come to be used again. Another thing it does is washes clothes and hangs them back up for kids. It also cooks popcorn and pours drinks. Another thing it does is dusting, it will dust anything for you. The simple machines we used were the wheel and axle, inclined plane, just wheels, pulleys, and gears.

This is the Chore 5, 000. He can clean your room. It can take the trash out and do other chores. He is made of gears, screws and pulleys.