Presentation on theme: "Warm Up 1. What simple machine is a ladder?"— Presentation transcript:
1 Warm Up 1. What simple machine is a ladder? 2. What simple machine is an inclined plane wrapped around a pole?What simple machine are steps .What simple machine is a shark tooth?What simple machine is a pair of scissors?What simple machine is a mini blind?What simple machine is a rake?What simple machine is a nail?What simple machine is a doorknob?What simple machine is a baseball bat?
4 Simple MachinesThere are six types of machines that scientists call “simple machines.” All machines, no matter how large or complicated, are made up of combinations of these six machines: the incline plane, the wedge, the screw, the lever, the wheel and axle, and the pulley.WHEEL & AXLE
6 Incline PlaneAn incline plane is the simplest of all machines. It consists of a ramp or a similar wedge-shaped device, that makes doing work easier.
7 Inclined means tilted and plane means flat, so any tilted, flat surface is an inclined plane. A ramp, is an incline plane.The length of the plane is the effort distance,The height the plane is raised is the resistance distance.
8 WedgeA wedge is an incline plane that moves. Material is moved up an inclined plane, but a wedge is moved through material.
9 A nail is a wedge when hammered into a board, the pointed or sloping end of the nail moves through the material of the board.An axe is a wedge used for splitting wood.
10 ScrewA screw is an inclined plane wrapped around a cylinder, forming spiraling ridges.
11 A screw rotates, and with each turn moves a certain distance into material.
12 The distance the screw moves depends on the screw’s pitch. The pitch is the distance between the threads, which are the ridges winding around the screw.pitch
13 The smaller the pitch, the smaller the distance the screw moves, but the greater the mechanical advantage of the screw.Thus a screw with a small pitch is easier to turn.
15 LeverA lever is a bar that is free to rotate about a fixed point called the fulcrum.fulcrum
16 Levers are divided into three groups based on the location of the fulcrum, the resistance force and the effort force.Three groups of leversFirst Class LeverSecond Class LeverThird Class LeverResistanceEffortResistanceResistanceFulcrumFulcrumFulcrumEffortEffort
17 First Class Lever In a first class lever, the fulcrum is in-between the effort force and the resistance force.EffortResistanceEffortResistanceFulcrum
18 Third Class Lever In the third class lever, the effort force is situated between the fulcrum and the resistance force.Resistancefulcrumeffort forceresistance forceEffortFulcrum
19 Second Class LeverIn a second class lever, the resistance force or load is situated between the fulcrum and the effort force.Example: WheelbarrowThe fulcrum is the wheel and the resistance (load) in a wheelbarrow is the object being moved while the person pushing the barrow supplies the effort.ResistanceEffortFulcrum
20 Warm Up What is an example of a third class lever? Levers are divided into three groups based on what three criteria?What is an inclined plane that moves?The distance between the threads on a screw is known as _________ ?What is an example of a second class lever?T or F The smaller the pitch of a screw, the less of a mechanical advantage it will have.The length of a plane is known as the ______ ?What is an example of a first class lever?The fixed point that a lever is free to move about is called a ____________.What is the simplest of all machines?
21 Wheel and Axle A wheel and axle is a lever that rotates in a circle. They are made of parts that move in two circles: an axle, which moves in a small circle and the wheel, which moves in a larger circle.
22 The wheel is not always like a wheel on a car For example, a screwdriver, a steering wheel and the crank in this diagram are examples of a wheel and axle machine. When you turn the wheel, your effort force moves in a larger circle than does the axle.axlewheel(crank)loadThe screwdriver is a wheel & axle, with the handle as the wheel.
23 Pulley A pulley is a lever that rotates around a fixed point. It is made of a wheel, usually grooved, that holds a cord.
24 Pulleys can be fixed or moveable Fixed PulleysThe fixed pulley is attached to an unmovable object such as a ceiling, and acts as a first class lever with the fulcrum being located at the axis but with a minor change, the bar becomes a rope.A fixed pulley is the only pulley that when used individually, uses more effort than the load to lift the load from the ground.Fulcrum
25 MoveablePulleysA movable pulley is a pulley that moves with the load.The movable pulley allows the effort to be less than the weight of the load. The movable pulley also acts as a second class lever. The load is between the fulcrum and the effort.The advantage of a movable pulley is that you use less effort to pull the load.The disadvantage of a movable pulley is that you have to pull or push the pulley up or down.The pulley and theload move downThe pulley and theload move up
26 Block and Tackle Pulley System Uses more than one moveable pulley to reduce the amount of force needed to lift a load.The more pulleys that are used, the smaller the applied force but the farther the rope must be pulled to move the load a certain distance.
29 Cool Down ReviewLevers are divided into three groups based on what three criteria?The length of a plane is known as the ______ ?The fixed point that a lever is free to move about is called a ____________.The distance between the threads on a screw is known as _________ ?The larger the (above) of a screw, the (less/more) of a mechanical advantage it will have.What is the advantage and disadvantage of a movable pulley.What simple machine is an inclined plane wrapped around a pole?Name the six simple machinesThe height of an inclined plane is the ___________.Effort force, resistance force, or fulcrum, which is in the middle of a third class lever?