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# Force

## on Jan 02, 2010

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## ForcePresentation Transcript

• Force, Motion, Energy, Matter
• Magnets
Magnets have an effect on some materials.
Magnets can make things move.
Magnets can push/pull or attract/repel things with containing iron.
Vocabulary: attraction-nonattraction
metal – nonmetal
magnetic - nonmagnetic
north and south poles
opposites
• Magnets have useful applications.
We use magnets to hang pictures on our refrigerators.
Magnetized screwdrivers help hold the screw in place.
A compass has a magnetized needle pointing north.
Magnets hold the lids from cans when using a can opener.
• The Six Simple Machines
Work, in physics, is a result of a force moving an object through a distance against a resistance. Work is always done by some agent, such as a person or a machine. This agent produces the force that causes the movement.
• Another Definition
Force is a push or a pull. In your everyday life, you experience a variety of forces. You apply a force to a ball when you throw it up in the air. As the ball rises, the force of gravity slows it down. As the ball descends, gravity makes it fall more rapidly. When you catch the ball, it applies a downward force to your hands. But your hands apply an upward force to the ball to stop it.
• Six Simple Machines
The six simple machines help us do work..
The six simple machines help to add force to help move something.
The six simple machines are:
lever, screw, pulley, wheel and axle, inclined plane, and wedge
• The Lever
Lever, is one of the six simple machines for performing work. It consists of a rod or bar that rests and turns on a support called a fulcrum. A force of effort is applied at one end of the rod to lift a load placed at the other end. A lever can help lift a weight with less effort. Prying something loose with a crowbar is using a lever. Some machines, such as a catapult, use a lever to hurl objects.
• Three Classes of Levers
First-class levers – the fulcrum is in the middle like a seesaw,crowbar, or balance scale.
Second-class levers- the load is in the middle like a wheel barrow, or a nutcracker.
Third-class levers – the effort is in the middle like a broom or a rake.
• First-class Lever
Effort
Fulcrum
• Screw
Screw is an inclined plane wrapped in a spiral around a shaft. The screw is one of the six simple machines developed in ancient times.
• Wedge
Wedge is a device that has two or more sloping surfaces that taper either to a sharp edge or to a point. Wedges are used to split or pierce materials, and to adjust the positions of heavy objects. Knives, chisels, axes, pins, needles, and nails are wedges.
• Inclined Plane
Inclined planeis a device used to raise heavy loads with relatively small forces. For example, pushing a load up a ramp onto a platform requires less force than lifting the load onto the platform.
Ramps and steps are forms of inclined planes.
• Wheel and Axle
Wheel and axle is a mechanical device used in lifting loads. It is one of the six simple machines developed in ancient times and ranks as one of the most important inventions in history. Sometimes teeth or cogs may be placed around the edge of the wheel, as in a cogwheel, or on the sprocket wheel of a bicycle.
• Pulleys
Pulley is a wheel over which a rope or belt is passed for the purpose of transmitting energy and doing work.
• Different Kinds of Motion
Objects may have straight, circular, or back and forth motions or movements.
Objects vibrate like the strings on a guitar.
Pushes or pulls can change the movement of an object.
You can see movement or motion anywhere.
• Matter, the substance of which all objects are made.
Matter can either be a solid, liquid, or gas.
Matter has mass and volume.
Objects are made of smaller parts
These parts are too small to be seen without magnification.
Physical properties remain the same as the material is reduced in size.
• Physical Properties of Matter
Form – flexible,stiff, straight, curved
Color – eight basic colors
Shape –circle, triangle, square
Texture – rough, smooth, hard, soft,
Size and weight –big, little, heavy, thin, etc
Position – over, under, in, out
Speed – fast, slow
• Water, Water, Water
Water occurs in three different forms.
Solid – ice, snow, hail, frost
Liquid- drinking water
Gas- steam,
The natural flow of water is down hill.
Some materials float, while others sink.
Some liquids will mix with water, like vinegar.
Some liquids will not mix with water, like oil.